Method for recovering iron-aluminum slag in whole chain integration and application thereof

Abstract

The present application provides a kind of full chain integrated recovery iron aluminum slag method, comprising the following steps: S1: iron aluminum slag is mixed with first lye and carries out first alkali leaching reaction, after solid-liquid separation, obtain first metal hydroxide residue and first alkali leaching solution;S2: the first metal hydroxide residue is mixed with second lye and carries out second alkali leaching reaction, after solid-liquid separation, obtain aluminate solution and second metal hydroxide residue;S3: the second metal hydroxide residue is made pulp, after adding acid and carrying out acid solution, add phosphate, seed and complexing agent and carry out iron precipitation reaction, after solid-liquid separation, obtain iron phosphate residue and nickel cobalt manganese extraction front liquid, after calcining the iron phosphate residue, obtain anhydrous iron phosphate.The method can achieve full recovery of metal elements, and the recovered products can be applied to existing industrial chain.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resource recycling, and particularly relates to a method for fully-chain integrated recovery of iron-aluminum slag and application. BACKGROUND

[0002] In the process of preparing ternary positive electrode precursors from waste ternary lithium batteries, a common process flow is: pretreatment-leaching-extraction-synthesis of ternary precursors. Among them, iron and aluminum removal is a very important step in leaching impurities, and iron and aluminum slag, as the only outlet for iron and aluminum, often has problems of large output and high processing cost. Therefore, it is of great significance to recover or utilize resources of metal elements in iron and aluminum slag. In the existing technology, there are the following problems in the wet extraction of metal elements in iron and aluminum slag: (1) low recovery rate of metal elements, no recovery of nickel, cobalt, manganese and lithium in iron and aluminum slag; in order to obtain high-quality single metal element product, another metal element is sacrificed; for example, in one existing technology, iron and aluminum slag is used to prepare hematite, and the aluminum element in the iron and aluminum slag is not utilized; for example, in another existing technology for comprehensive utilization of iron and aluminum slag, the product of the process is sodium aluminum sulfate dodecahydrate, and the iron resource is not recovered; (2) the recovered product cannot be self-named, but is processed by external sale, and due to the lack of effective recycling channels, the resource utilization rate is low.

[0003] In view of this, the present application is proposed. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a method for fully-chain integrated recovery of iron and aluminum slag and application, which can achieve full recovery of metal elements, and the recovered product can be applied to the existing industrial chain.

[0005] According to a first aspect of the present application, a method for recovering iron and aluminum slag is proposed, comprising the following steps:

[0006] S1: mixing iron and aluminum slag with a first alkali solution for a first alkali leaching reaction, and after solid-liquid separation, obtaining a first metal hydroxide slag and a first alkali leaching solution;

[0007] S2: mixing the first metal hydroxide slag with a second alkali solution for a second alkali leaching reaction, and after solid-liquid separation, obtaining an aluminate solution and a second metal hydroxide slag;

[0008] S3: slurry-making the second metal hydroxide slag, adding acid for acid dissolution, and then adding a phosphate, a seed crystal and a complexing agent for iron precipitation, and after solid-liquid separation, obtaining a phosphorus iron slag and a nickel-cobalt-manganese extraction solution, and calcining the phosphorus iron slag to obtain anhydrous phosphorus iron.

[0009] In some embodiments, in step S1, the pH value of the first alkaline solution is 9.5-11; and / or, the solid-liquid mass ratio of the iron-aluminum residue to the first alkaline solution is 1:(5-10).

[0010] In some embodiments, the first alkaline solution is a sodium hydroxide solution.

[0011] In some embodiments, step S1 further comprises: washing the first metal hydroxide residue with the first alkaline solution, and incorporating the obtained washing solution into the first alkaline leaching solution.

[0012] In some embodiments, step S1 further comprises: adding sulfuric acid to the first alkaline leaching solution to obtain a neutralization solution, concentrating the neutralization solution to obtain a crystallization solution, freezing and crystallizing the crystallization solution, and solid-liquid separation to obtain sodium sulfate crystals and a lithium precipitation mother liquor. The lithium precipitation mother liquor obtained in this process can be incorporated into a lithium carbonate production workshop.

[0013] In some preferred embodiments, the pH value of the neutralization solution is 6.5-7.5.

[0014] In some preferred embodiments, the concentration of sodium ions in the crystallization solution is greater than 1.8 mol / L.

[0015] In some preferred embodiments, the freezing and crystallization temperature is 5-10°C.

[0016] In some embodiments, in step S2, the second alkaline solution is a sodium hydroxide solution with a pH value of 13 or above, and the molar ratio of sodium elements in the sodium hydroxide solution to aluminum elements in the first metal hydroxide residue is (1.5-3):1.

[0017] In some embodiments, the temperature of the first and second alkaline leaching reactions is independently selected from 60-80°C, and the time of the first and second alkaline leaching reactions is independently selected from 2-4 h.

[0018] In some embodiments, step S2 further comprises: washing the second metal hydroxide residue with water, and incorporating the obtained washing water into the first alkaline leaching solution.

[0019] In some embodiments, step S2 further comprises: adding aluminum hydroxide seeds to the aluminate solution for seeding, and obtaining aluminum hydroxide crystals after solid-liquid separation.

[0020] In some preferred embodiments, the aluminate solution is a sodium aluminate solution, and the caustic ratio of the sodium aluminate solution is 1.4-1.65, wherein the concentration of aluminum oxide is 140-180 g / L. The present application adopts Bayer process crystallization to prepare aluminum hydroxide crystals, wherein the caustic ratio is the molar ratio of sodium oxide to aluminum oxide in the sodium aluminate solution.

[0021] In some preferred embodiments, the feeding ratio of the sodium aluminate solution to the aluminum hydroxide seed is 1 L: (2-10) g.

[0022] In some preferred embodiments, the temperature of the seed is 30-60°C, and the time is 24-60 h.

[0023] In some embodiments, in step S3, the pulping comprises mixing the second metal hydroxide residue with water at a solid-liquid mass ratio of 1: (5-10) to pulp.

[0024] In some embodiments, in step S3, the acid dissolution comprises stirring at pH 1-2.5 until the second metal hydroxide residue is completely dissolved; and / or, the temperature of the acid dissolution is 25-60°C.

[0025] In some embodiments, in step S3, the acid is selected from at least one of sulfuric acid, phosphoric acid, hydrochloric acid, or nitric acid.

[0026] In some embodiments, in step S3, the phosphate salt is selected from at least one of sodium dihydrogen phosphate, sodium monohydrogen phosphate, ammonium dihydrogen phosphate, or ammonium monohydrogen phosphate.

[0027] In some embodiments, in step S3, the phosphate salt is added in an amount such that the molar ratio of phosphorus to iron in the reaction solution n(P):n(Fe) is (1.1-1.5):1.

[0028] In some embodiments, in step S3, the seed is iron phosphate dihydrate with a particle size of less than 1.5 μm; and / or, the seed is fed at a solid-liquid ratio (2-8):100 g / mL. The above solid-liquid ratio is the solid-liquid ratio of the seed to the acid-dissolved solution after acid dissolution of the second metal hydroxide residue.

[0029] In some embodiments, in step S3, the complexing agent is a water-soluble o-diphenol compound; and / or, the concentration of the complexing agent in the reaction solution is 5-15 g / L.

[0030] In some preferred embodiments, the complexing agent is selected from at least one of o-diphenol, 4-methylcatechol, 2,3-dihydroxybenzoic acid, dopamine hydrochloride, dopamine, 2,3,4-trihydroxybenzoic acid, o-phenyl triol, or 1,2,4-benzene triol.

[0031] In some embodiments, in step S3, the temperature of the iron precipitation reaction is 70-90°C, the reaction time is 1-4 h, and the stirring speed is 200-400 rpm.

[0032] According to a second aspect of the present invention, the application of the method described in the first aspect of the present invention in the recycling of waste lithium batteries is proposed. Since the main power batteries on the market are ternary lithium batteries and lithium iron phosphate batteries, most battery recycling industries include recycling lines for both types of batteries. The product obtained by the method for recycling iron and aluminum slag proposed in this invention can be automatically collected on the production line, saving many steps and improving resource utilization.

[0033] According to one embodiment of the present invention, at least the following beneficial effects are achieved:

[0034] 1. The method provided by this invention recovers small amounts of nickel, cobalt, manganese and lithium elements remaining in iron and aluminum slag, and can be integrated into the nickel, cobalt and manganese recovery section and lithium salt production workshop to further improve the recovery rate of the production line.

[0035] 2. The method provided by this invention can achieve full recovery of metal elements in iron and aluminum slag, including nickel, cobalt, manganese, lithium, iron, and aluminum.

[0036] 3. The product obtained by the method provided by this invention can be directly applied in the battery recycling production line, avoiding drying and packaging for external sale, thus improving safety and resource utilization.

[0037] 4. This invention uses a one-step iron deposition method to prepare iron phosphate crystals, which are then calcined to obtain battery-grade anhydrous iron phosphate. The one-step iron deposition method has the following advantages: ① The nucleation efficiency of dihydrate iron phosphate is relatively low, therefore adding seed crystals can accelerate the nucleation efficiency; ② Adding Fe... 3+ Complexing agents with good complexing properties allow free Fe in the reaction solution to be released. 3+ The decrease in temperature reduces the growth rate of crystals, avoids the formation of amorphous iron phosphate, reduces crystal defects in hydrated iron phosphate crystals, and helps to reduce the amount of nickel, cobalt, and manganese carried in iron phosphate slag, thereby improving the separation rate.

[0038] 5. The nickel-cobalt-manganese pre-extraction liquid recovered by the method provided by this invention contains a complexing agent and is incorporated into the extraction section of the wet extraction of ternary cathode materials, which can improve the partition coefficient of iron in the organic phase, thereby improving the extraction and separation efficiency. Attached Figure Description

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0040] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention;

[0041] Figure 2 This is a flow chart of the extraction process for the nickel-cobalt-manganese extraction pre-extraction solution.

[0042] Figure 3The XRD pattern of the product obtained by the iron precipitation reaction in Example 1, Comparative Example 4, and Comparative Example 5 of the present application. DETAILED DESCRIPTION

[0043] The concept and technical effects of the present application will be described below in conjunction with examples, so as to fully understand the purpose, features and effects of the present application.

[0044] The raw materials, reagents or devices used in the following examples are commercially available or can be obtained by known methods unless otherwise specified.

[0045] Test description: ICP is used to measure the metal ion concentration of solids and liquids; ultraviolet spectrophotometer is used to measure the complexing agent concentration in the solution.

[0046] Example 1

[0047] The present embodiment provides a method for recovering iron and aluminum slag in a full-chain integrated manner, as shown in the following steps: Figure 1 The present embodiment provides a method for recovering iron and aluminum slag in a full-chain integrated manner, as shown in the following steps:

[0048] (1) The iron and aluminum slag is mixed with a sodium hydroxide solution with a pH of 10 at a mass ratio of 1:8 to prepare a pulp, and then the temperature is raised to 70°C for a first alkali leaching reaction, the reaction time is 3h, after solid-liquid separation, a first metal hydroxide slag and a first alkali leaching solution are obtained, the obtained first metal hydroxide slag is washed with the above-mentioned sodium hydroxide solution, and the washing liquid is added to the first alkali leaching solution.

[0049] The metal element content of the iron and aluminum slag measured by ICP is as follows:

[0050]

[0051] The metal element content of the first metal hydroxide slag measured by ICP is as follows:

[0052]

[0053] (2) The first metal hydroxide slag is mixed with a sodium hydroxide solution with a pH of 13, the molar ratio of sodium element in the sodium hydroxide solution to the molar amount of aluminum element in the first metal hydroxide slag is 2:1, and the temperature is raised to 70°C for a second alkali leaching reaction, the reaction time is 3h, after solid-liquid separation, a sodium aluminate solution and a second metal hydroxide slag are obtained, the obtained second metal hydroxide slag is washed with water for standby, and the washing liquid is added to the first alkali leaching solution.

[0054] The metal element content of the second metal hydroxide slag measured by ICP is as follows:

[0055]

[0056] (3) The second metal hydroxide residue obtained in step (2) is mixed with water at a solid-liquid mass ratio of 1:8 to prepare a slurry, and then sulfuric acid is added. The solution is stirred at a pH of 1.8 and a temperature of 60°C until the second metal hydroxide residue is completely dissolved. Then, sodium phosphate monohydrate, iron phosphate dihydrate seed crystals (particle size of 800 nm to 1.2 μm), and a complexing agent, catechol, are added for iron precipitation. The amount of sodium phosphate monohydrate added is based on a molar ratio of phosphorus to iron in the reaction solution of n(P):n(Fe) = 1.3:1. The amount of iron phosphate dihydrate seed crystals added is based on a solid-liquid ratio of 5 g:100 mL (the solid-liquid ratio is the ratio of the amount of iron phosphate dihydrate seed crystals to the amount of acid solution after the second metal hydroxide residue is completely dissolved, and the same applies below). The concentration of catechol in the reaction solution is 10 g / L. The temperature for the iron precipitation reaction is 80°C, the reaction time is 3 h, and the stirring speed is 300 rpm. After solid-liquid separation, iron phosphate residue and nickel-cobalt-manganese extraction feed solution are obtained. The XRD pattern of the iron phosphate residue is shown in FIG. 6, and the anhydrous iron phosphate residue is calcined at 600°C for 2 h to obtain battery-grade anhydrous iron phosphate. Figure 3

[0057] The metal element content of the anhydrous iron phosphate is as follows:

[0058]

[0059] The concentrations of key components in the nickel-cobalt-manganese extraction feed solution are as follows:

[0060]

[0061] (4) Sulfuric acid is added to the first alkali leaching solution obtained in step (1) to perform a neutralization reaction until the pH of the solution is 7, thereby obtaining a neutralized solution. The neutralized solution is heated and concentrated until the concentration of sodium ions is 2.5 mol / L, thereby obtaining a crystallization solution. The crystallization solution is cooled to 10°C and maintained for 24 h to perform a freeze crystallization. After solid-liquid separation, sodium sulfate crystals and lithium precipitation mother liquor are obtained. The sodium sulfate crystals are washed with 10°C cold water and then dried. The obtained lithium precipitation mother liquor is transferred to a lithium carbonate production workshop.

[0062] The metal ion concentrations in the lithium precipitation mother liquor are as follows:

[0063]

[0064] (5) Sodium aluminate solution obtained in step (2) is added with sodium hydroxide to adjust the caustic ratio of the sodium aluminate solution to 1.52, and the concentration of aluminum oxide is 161 g / L. Then, aluminum hydroxide seed crystals are added for seed precipitation. After solid-liquid separation, the solid phase is washed with pure water and dried to obtain aluminum hydroxide crystals. The remaining solution is continuously returned to the second alkali leaching reactor. The seed precipitation decomposition rate is 46%. The ratio of the amount of sodium aluminate solution to the amount of aluminum hydroxide seed crystals is 1 L:6 g. The seed precipitation temperature is 50°C, and the time is 24 h.

[0065] ​The aluminum hydroxide seed crystals are aluminum hydroxide crystals prepared according to the same process, collectively referred to as aluminum hydroxide crystals, and the parameters measured according to the GB / T4294-2010 standard are as follows:

[0066]

[0067] Example 2

[0068] The present embodiment provides a method for recovering iron-aluminum slag in a full-chain integrated manner, which specifically comprises the following steps:

[0069] (1) The iron-aluminum slag is mixed with a sodium hydroxide solution with a pH of 9.5 at a mass ratio of 1:10 to prepare a slurry, and then the temperature is raised to 80°C for a first alkali leaching reaction, and the reaction time is 4 h. After solid-liquid separation, a first metal hydroxide residue and a first alkali leaching solution are obtained. The obtained first metal hydroxide residue is washed with the above-mentioned sodium hydroxide solution, and the washing solution is added to the first alkali leaching solution.

[0070] The metal element content of the iron-aluminum slag measured by ICP is as follows:

[0071]

[0072] The metal element content of the first metal hydroxide residue measured by ICP is as follows:

[0073]

[0074] (2) The first metal hydroxide residue is mixed with a sodium hydroxide solution with a pH of 14, and the molar ratio of sodium element in the sodium hydroxide solution to the molar amount of aluminum element in the first metal hydroxide residue is 1.5:1. The temperature is raised to 80°C for a second alkali leaching reaction, and the reaction time is 2 h. After solid-liquid separation, a sodium aluminate solution and a second metal hydroxide residue are obtained. The obtained second metal hydroxide residue is washed with water for standby, and the washing solution is added to the first alkali leaching solution.

[0075] The metal element content of the second metal hydroxide residue measured by ICP is as follows:

[0076]

[0077] (3) The second metal hydroxide residue obtained in step (2) is mixed with water at a solid-liquid mass ratio of 1:10 to prepare a slurry, then hydrochloric acid is added, and stirring is carried out at a pH of 1 and a temperature of 40°C until the second metal hydroxide residue is completely dissolved, then a sodium dihydrogen phosphate, iron phosphate dihydrate seed crystal (particle size of 1-1.5 μm) and a complexing agent 2,3-dihydroxybenzoic acid are added to carry out an iron precipitation reaction, the addition amount of sodium dihydrogen phosphate is added according to the molar ratio n(P):n(Fe) of phosphorus to iron in the reaction solution is 1.1:1, the addition amount of iron phosphate dihydrate seed crystal is 8g:100mL, and the concentration of 2,3-dihydroxybenzoic acid in the reaction solution is 5g / L. The temperature of the iron precipitation reaction is 70°C, the reaction time is 4h, and the stirring speed is 200rpm. After solid-liquid separation, iron phosphate residue and nickel-cobalt-manganese extraction feed liquid are obtained, and the iron phosphate residue is washed and calcined at 600°C for 2h to obtain battery-grade anhydrous iron phosphate.

[0078] The metal element content analysis of anhydrous iron phosphate is as follows:

[0079]

[0080] The key component concentration of the nickel-cobalt-manganese extraction feed liquid is as follows:

[0081]

[0082] (4) Sulfuric acid is added to the first alkali leaching solution obtained in step (1) to carry out a neutralization reaction until the pH of the solution is 6.5, thereby obtaining a neutralization liquid; the neutralization liquid is heated and concentrated until the concentration of sodium ions is 1.84 mol / L, thereby obtaining a crystallization liquid; the crystallization liquid is cooled to 10°C and kept for 24h to carry out a freeze crystallization, and after solid-liquid separation, sodium sulfate crystals and lithium precipitation mother liquor are obtained, the sodium sulfate crystals are washed with 10°C cold water and then dried; and the obtained lithium precipitation mother liquor is introduced into a lithium carbonate production workshop.

[0083] The metal ion concentration of the lithium precipitation mother liquor is as follows:

[0084]

[0085] (5) Sodium aluminate solution obtained in step (2) is added with sodium hydroxide to adjust the caustic ratio of the sodium aluminate solution to 1.4, and the concentration of aluminum oxide is 140g / L, then aluminum hydroxide seed crystal is added for seed precipitation, after solid-liquid separation, the solid phase is washed with pure water, dried to obtain aluminum hydroxide crystals, and the remaining solution is continuously returned to the second alkali leaching reactor, and the seed precipitation decomposition rate is 37%. The feeding amount ratio of the sodium aluminate solution to the aluminum hydroxide seed crystal is 1L:10g. The seed precipitation temperature is 30°C, and the time is 60h.

[0086] The aluminum hydroxide seed crystal is aluminum hydroxide crystals prepared according to the same process, collectively referred to as aluminum hydroxide crystals, and the parameters measured according to GB / T4294-2010 standard are as follows:

[0087]

[0088] Example 3

[0089] The embodiment provides a method for recovering iron-aluminum slag in an integrated manner, and specifically comprises the following steps.

[0090] (1) The iron-aluminum slag is mixed with a sodium hydroxide solution with a pH of 11 at a mass ratio of 1:5 to prepare a pulp, and then the temperature is increased to 60 DEG C to perform a first alkali leaching reaction, the reaction time is 2 h, after solid-liquid separation, a first metal hydroxide residue and a first alkali leaching solution are obtained, the obtained first metal hydroxide residue is washed with the above-mentioned sodium hydroxide solution, and the washing solution is added to the first alkali leaching solution.

[0091] The metal element content of the iron-aluminum slag measured by ICP is as follows:

[0092]

[0093] The metal element content of the first metal hydroxide residue measured by ICP is as follows:

[0094]

[0095] (2) The first metal hydroxide residue is mixed with a sodium hydroxide solution with a pH of 13.5, the molar ratio of sodium element in the sodium hydroxide solution to the molar amount of aluminum element in the first metal hydroxide residue is 3:1, the temperature is increased to 60 DEG C to perform a second alkali leaching reaction, the reaction time is 4 h, after solid-liquid separation, a sodium aluminate solution and a second metal hydroxide residue are obtained, the obtained second metal hydroxide residue is washed with water for standby, and the washing solution is added to the first alkali leaching solution.

[0096] The metal element content of the second metal hydroxide residue measured by ICP is as follows:

[0097]

[0098] (3) The second metal hydroxide residue obtained in step (2) is mixed with water at a solid-liquid mass ratio of 1:5 to prepare a slurry, then hydrochloric acid is added, and the second metal hydroxide residue is completely dissolved at a pH of 2.5 and a temperature of 25°C, then a ferric precipitation reaction is carried out by adding ammonium dihydrogen phosphate, iron phosphate dihydrate seed crystals (particle size of 500-800 nm) and a complexing agent dopamine hydrochloride, the ammonium dihydrogen phosphate is added in an amount such that the molar ratio of phosphorus to iron in the reaction solution n(P):n(Fe) is 1.5:1, the iron phosphate dihydrate seed crystals are added at a solid-liquid ratio of 2g:100mL, and the concentration of dopamine hydrochloride in the reaction solution is 15g / L. The temperature of the ferric precipitation reaction is 90°C, the reaction time is 1h, and the stirring speed is 400rpm. After solid-liquid separation, iron phosphate residue and nickel-cobalt-manganese extraction feed solution are obtained, and the iron phosphate residue is washed and then calcined at 600°C for 2h to obtain battery-grade anhydrous iron phosphate.

[0099] The metal element content of the anhydrous iron phosphate is analyzed as follows:

[0100]

[0101] The key component concentrations of the nickel-cobalt-manganese extraction feed solution are as follows:

[0102]

[0103] (4) Sulfuric acid is added to the first alkali leaching solution obtained in step (1) to carry out a neutralization reaction until the pH of the solution is 7.5, thereby obtaining a neutralization solution; the neutralization solution is heated and concentrated until the concentration of sodium ions is 2.81mol / L, thereby obtaining a crystallization solution; the crystallization solution is cooled to 10°C and kept for 24h to carry out a freeze crystallization, and after solid-liquid separation, sodium sulfate crystals and lithium precipitation mother liquor are obtained, the sodium sulfate crystals are washed with 10°C cold water and then dried; the obtained lithium precipitation mother liquor is introduced into a lithium carbonate production workshop.

[0104] The metal ion concentrations of the lithium precipitation mother liquor are as follows:

[0105]

[0106] (5) Sodium aluminate solution obtained in step (2) is added with sodium hydroxide to adjust the caustic ratio of the sodium aluminate solution to 1.65, and the concentration of aluminum oxide is 180g / L, then aluminum hydroxide seed crystals are added for seed precipitation, after solid-liquid separation, the solid phase is washed with pure water, dried to obtain aluminum hydroxide crystals, and the remaining solution is continuously returned to the second alkali leaching reactor, and the seed precipitation decomposition rate is 42%. The feeding amount ratio of the sodium aluminate solution to the aluminum hydroxide seed crystals is 1L:2g. The seed precipitation temperature is 60°C, and the time is 48h.

[0107] The aluminum hydroxide seed crystals are aluminum hydroxide crystals prepared according to the same process, collectively referred to as aluminum hydroxide crystals, and the parameters measured according to the GB / T4294-2010 standard are as follows:

[0108]

[0109] Example 4

[0110] The embodiment provides a method for recovering iron-aluminum slag in a whole chain, which is different from the embodiment 1 in that the pH value of the sodium hydroxide solution in step (2) is 14.

[0111] The metal element content of the second metal hydroxide slag is measured by ICP as follows:

[0112]

[0113] Example 5

[0114] The embodiment provides a method for recovering iron-aluminum slag in a whole chain, which is different from the embodiment 1 in that the adding amount of the iron phosphate dihydrate seed in step (3) is 2g:100mL according to the solid-liquid ratio.

[0115] The metal element content of the anhydrous iron phosphate is analyzed as follows:

[0116]

[0117] The concentration of key components of the nickel-cobalt-manganese pre-extraction solution is as follows:

[0118]

[0119] Example 6

[0120] The embodiment provides a method for recovering iron-aluminum slag in a whole chain, which is different from the embodiment 1 in that the adding amount of the iron phosphate dihydrate seed in step (3) is 8g:100mL according to the solid-liquid ratio.

[0121] The metal element content of the anhydrous iron phosphate is analyzed as follows:

[0122]

[0123] The concentration of key components of the nickel-cobalt-manganese pre-extraction solution is as follows:

[0124]

[0125] Example 7

[0126] The embodiment provides a method for recovering iron-aluminum slag in a whole chain, which is different from the embodiment 1 in that the concentration of the complexing agent in the reaction solution in step (3) is 5g / L.

[0127] The metal element content of the anhydrous iron phosphate is analyzed as follows:

[0128]

[0129] The concentrations of key components in the nickel-cobalt-manganese extraction feed liquid are as follows:

[0130]

[0131] Example 8

[0132] This example provides a method for recycling iron-aluminum slag in an entire chain, which is different from example 1 in that the concentration of the complexing agent in the reaction liquid in step (3) is 15 g / L.

[0133] The metal element content analysis of the anhydrous iron phosphate is as follows:

[0134]

[0135] The concentrations of key components in the nickel-cobalt-manganese extraction feed liquid are as follows:

[0136]

[0137] Comparative Example 1

[0138] This comparative example provides a method for recycling iron-aluminum slag, which is different from example 1 in that the pH value of the sodium hydroxide solution in step (1) is 8.5.

[0139] The metal element content of the first metal hydroxide slag measured by ICP is as follows:

[0140]

[0141] Comparative Example 2

[0142] This comparative example provides a method for recycling iron-aluminum slag, which is different from example 1 in that the pH value of the sodium hydroxide solution in step (2) is 12.

[0143] The metal element content of the second metal hydroxide slag measured by ICP is as follows:

[0144]

[0145] Comparative Example 3

[0146] The comparative example provides a method for recovering iron-aluminum slag, which is different from example 1 in that step (3) adopts the jarosite method to precipitate iron, and the specific process is as follows: water is added to the second metal hydroxide slag to prepare a slurry (the mass ratio of the second metal hydroxide slag to water is 1:6), then concentrated sulfuric acid is added to adjust the pH to 1.5 for acid leaching and dissolution, after solid-liquid separation, sodium carbonate is added to the obtained acid leaching solution to adjust and maintain the pH at 2.2, and the temperature is raised to 95°C for 5h to obtain jarosite precipitate, and the reaction principle is 6Fe 3+ + 2Na + + 4SO4 2- + 12H2O == Na2Fe6(SO4)4(OH) 12 + 12H + The mother liquor of the precipitated iron enters the extraction section as the nickel-cobalt-manganese extraction feed liquid.

[0147] Comparative example 4

[0148] The comparative example provides a method for recovering iron-aluminum slag, which is different from example 1 in that step (3) does not add iron phosphate dihydrate seeds.

[0149] The metal element content analysis of anhydrous iron phosphate is as follows:

[0150]

[0151] The key component concentration of the nickel-cobalt-manganese extraction feed liquid is as follows:

[0152]

[0153] Since no seeds are added, the crystallization of iron phosphate dihydrate is difficult to nucleate, so most of the iron phosphate slag is amorphous, and its XRD pattern is as shown in Figure 3 , which has flocculation effect and carries a large amount of metal elements.

[0154] Comparative example 5

[0155] The comparative example provides a method for recovering iron-aluminum slag, which is different from example 1 in that step (3) does not add a complexing agent.

[0156] The metal element content analysis of anhydrous iron phosphate is as follows:

[0157]

[0158] The key component concentration of the nickel-cobalt-manganese extraction feed liquid is as follows:

[0159]

[0160] Without adding complexing agent, the precipitation of iron phosphate is too fast, and a lot of amorphous iron phosphate is produced, thus a large amount of metal elements is brought in, and the XRD pattern thereof is shown in Figure 1. Figure 3

[0161] Test Example

[0162] (1) Metal element recovery rate calculation

[0163] The content of each element of the iron-aluminum slag is calculated as the input amount, and the content of the main element of each product is measured as the recovery amount. The percentage of the recovery amount to the input amount is taken as the recovery rate. For example, the main element of the lithium precipitation mother liquor is Li, the concentration of lithium ions in the lithium precipitation mother liquor and the volume of the lithium precipitation mother liquor are measured to calculate the lithium recovery amount. For another example, the main element of the aluminum hydroxide is Al, the content of Al in the dried aluminum hydroxide crystal and the total mass are measured to calculate the aluminum recovery amount. For another example, the main element of the anhydrous iron phosphate is Fe, the content of Fe in the anhydrous iron phosphate and the total mass are measured to calculate the iron recovery amount. For another example, the main elements of the nickel-cobalt-manganese pre-extraction solution are Ni, Co and Mn, the concentrations of Ni, Co and Mn ions in the nickel-cobalt-manganese pre-extraction solution and the volume of the nickel-cobalt-manganese pre-extraction solution are measured to calculate the recovery amounts of Ni, Co and Mn.

[0164]

[0165] (2) Improvement of extraction section efficiency

[0166] The nickel-cobalt-manganese pre-extraction solution is extracted according to the process flow shown in Figure 2, and the content of iron ions in the recovery solution obtained by the first stripping is studied, which is specifically described as follows. Figure 2

[0167] The first extraction uses P204 as the extractant and kerosene as the diluent, and the mass ratio of P204 to kerosene is 30%:70%, the saponification degree of P204 is 65%, five-stage countercurrent extraction is adopted, the obtained organic phase is subjected to five-stage stripping to obtain the first stripping solution, the stripping agent is dilute sulfuric acid, the content of iron ions in the first stripping solution after oil removal is detected, and the recovery rate is calculated accordingly; the raffinate (inorganic phase) enters the second extraction.

[0168] The second extraction uses P507 as the extractant and kerosene as the diluent, and the mass ratio of P507 to kerosene is 1:3, the saponification degree of P507 is 65%, five-stage countercurrent extraction is adopted, the obtained organic phase is subjected to five-stage stripping to obtain the second stripping solution, the stripping agent is dilute sulfuric acid; the raffinate (inorganic phase) is adsorbed by a resin, and the elution solution obtained by elution with dilute sulfuric acid is added to the second stripping solution, the content of nickel, cobalt and manganese in the second stripping solution after oil removal is detected, and the recovery rate of the metal elements in the nickel-cobalt-manganese pre-extraction solution is calculated accordingly.

[0169] ​​

[0170] Principle: catechol compounds form a complex with iron ions, reducing the water solubility of metal ions, catechol lipophilicity is stronger than hydrophilicity, so as a bridge to promote the process of iron ions into the organic phase, thereby improving the separation of iron and nickel, cobalt and manganese. See the table above, the comparative example 5 does not add complexing agent catechol compounds, so the recovery of iron decreases.

[0171] The above has been described in detail for the embodiments of the present application, but the present application is not limited to the above-mentioned embodiments, within the scope of knowledge possessed by those skilled in the art, various changes can also be made without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method of recycling iron-aluminum slag, characterized by, The method comprises the following steps: S1: mixing the iron-aluminum slag with a first alkali solution to perform a first alkali leaching reaction, and after solid-liquid separation, a first metal hydroxide residue and a first alkali leaching solution are obtained; S2: mixing the first metal hydroxide residue with a second alkali solution to perform a second alkali leaching reaction, and after solid-liquid separation, an aluminate solution and a second metal hydroxide residue are obtained; S3: slurry-making the second metal hydroxide residue, adding an acid to perform acid dissolution, and then adding a phosphate, a seed crystal and a complexing agent to perform a ferric precipitation reaction, and after solid-liquid separation, a ferric phosphate residue and a nickel-cobalt-manganese extraction solution are obtained, and the ferric phosphate residue is calcined to obtain anhydrous ferric phosphate; In step S1, the pH value of the first alkali solution is 9.5-11; and / or the solid-liquid mass ratio of the iron-aluminum slag to the first alkali solution is 1:(5-10); In step S3, the complexing agent is a water-soluble o-diphenol compound; and / or the concentration of the complexing agent in the reaction solution is 5-15 g / L.

2. The method of claim 1, wherein, In step S2, the second alkali solution is a sodium hydroxide solution with a pH of 13 or more, and the molar ratio of sodium in the sodium hydroxide solution to aluminum in the first metal hydroxide residue is (1.5-3):

1.

3. The method of claim 1, wherein, The temperature of the first alkali leaching reaction and the second alkali leaching reaction is independently selected from 60-80℃, and the time of the first alkali leaching reaction and the second alkali leaching reaction is independently selected from 2-4h.

4. The method of claim 1, wherein, Step S2 further comprises: adding aluminum hydroxide seed crystals to the aluminate solution to perform seed separation, and after solid-liquid separation, aluminum hydroxide crystals are obtained.

5. The method of claim 1, wherein, In step S3, the acid dissolution comprises: stirring at a pH of 1-2.5 until the second metal hydroxide residue is completely dissolved; and / or the temperature of the acid dissolution is 25-60℃.

6. The method of claim 1, wherein, In step S3, the seed crystal is iron phosphate dihydrate with a particle size of less than 1.5μm; and / or the seed crystal is added at a solid-liquid ratio of (2-8):100 g / mL.

7. The method of claim 1, wherein, In step S3, the temperature of the ferric precipitation reaction is 70-90℃, the reaction time is 1-4h, and the stirring speed is 200-400rpm.

8. Use of the method of any one of claims 1-7 in recycling waste lithium batteries.

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