Method for resource recovery of ferronickel

Abstract

This application provides a method for the resource utilization of nickel-iron alloys, belonging to the field of mining and metallurgy. The method includes: a leaching step: subjecting the nickel-iron alloy material to acid leaching in an inert atmosphere, followed by solid-liquid separation to obtain a leachate containing nickel salts and ferrous salts; a separation step: extracting the leachate with a first extractant to obtain a nickel-loaded organic phase and a raffinate containing ferrous salts; and a nickel salt preparation step: washing and back-extracting the nickel-loaded organic phase to obtain a nickel salt back-extraction solution. This application achieves efficient separation of nickel and iron in the resource utilization of nickel-iron alloys, obtaining high-quality nickel salts while reducing auxiliary material consumption, shortening the process flow, and significantly reducing equipment investment and operating costs.

Description

Technical Field

[0001] This invention belongs to the field of batteries, and particularly relates to a method for the resource utilization of nickel-iron alloy. Background Technology

[0002] With the increasing demand for nickel salts in new energy and other fields, the efficient conversion of nickel-iron alloys obtained from pyrometallurgical processes into nickel salts is of great significance. However, current technological approaches to achieve nickel-iron separation are often complex, generally suffering from limited iron removal efficiency, lengthy process flows, and the need to consume large amounts of neutralizing or extracting agents, resulting in poor overall process economy and high costs. Summary of the Invention

[0003] This application provides a method for the resource recovery of nickel-iron alloys, which aims to solve or at least alleviate one of the defects existing in the prior art.

[0004] This application provides a method for the resource recovery of nickel-iron alloy, including: Leaching process: The nickel-iron alloy material is subjected to acid leaching reaction in an inert atmosphere, and after solid-liquid separation, a leachate containing nickel salt and ferrous salt is obtained. Separation process: The leachate is extracted with the first extractant to obtain a nickel-loaded organic phase and a raffinate containing ferrous salts; Nickel salt preparation process: The nickel-loaded organic phase is washed and back-extracted to obtain nickel salt back-extraction solution.

[0005] The resource utilization method for nickel-iron alloy provided in this application involves acid leaching under an inert atmosphere, which dissolves the nickel-iron alloy while effectively inhibiting the oxidation of ferrous ions to obtain a leachate containing nickel salts and ferrous salts. In the separation process, a first extractant is used to extract the leachate, extracting nickel into the organic phase while leaving ferrous ions in the aqueous phase. This achieves highly selective separation of nickel from a large amount of ferrous ions, yielding a nickel-loaded organic phase and a raffinate mainly composed of ferrous salts. Subsequently, the nickel-loaded organic phase is washed and back-extracted to obtain a high-purity nickel salt product, while the ferrous-rich raffinate can be easily processed and effectively utilized, greatly improving resource utilization.

[0006] Therefore, this application reduces the extraction volume and significantly reduces the consumption of chemicals such as neutralizers and oxidizers by selectively extracting nickel, thereby obtaining high-quality nickel salts. This significantly shortens the process flow and reduces equipment investment and operating costs, resulting in excellent economic efficiency and environmental friendliness.

[0007] In some embodiments, the method further includes: a nickel salt purification step: using a second extractant to extract and remove impurities from the nickel salt back-extraction solution to obtain a purified nickel salt solution; and / or, a process for preparing iron oxide red: spraying the raffinate containing ferrous salts under an oxygen-containing atmosphere to obtain iron oxide red.

[0008] In some embodiments, the nickel salt purification process specifically includes: adjusting the pH value of the nickel salt back-extraction solution to 4.0-5.0; and using a second extractant to perform multi-stage countercurrent extraction of the pH-adjusted nickel salt back-extraction solution to obtain a cobalt salt solution and a purified nickel salt solution.

[0009] In some embodiments, the fractionation multi-stage countercurrent extraction sequentially includes: a saponification stage: pre-treating the second extractant with liquid alkali, wherein the O / A volume ratio of the second extractant to the liquid alkali is controlled at (20~30):1; an extraction stage: countercurrently extracting the nickel salt back-extraction solution with the pre-treated second extractant to obtain a cobalt-loaded organic phase and a purified nickel salt solution, wherein the O / A volume ratio of the pre-treated second extractant to the nickel salt back-extraction solution is controlled at (1.5~2.5):1; a washing stage: washing the cobalt-loaded organic phase with washing acid, wherein the O / A volume ratio of the cobalt-loaded organic phase to the washing acid is controlled at (8~12):1; and a back-extraction stage: back-extracting the washed cobalt-loaded organic phase with back-extraction acid, wherein the O / A volume ratio of the washed cobalt-loaded organic phase to the back-extraction acid is controlled at (8~12):1.

[0010] In some embodiments, the leaching process includes: preparing a slurry from the nickel-iron alloy material to obtain a slurry; placing the slurry in a reaction vessel, introducing an inert atmosphere and acid into the reaction vessel to carry out an acid leaching reaction, and obtaining a leachate containing nickel salts and ferrous salts after solid-liquid separation.

[0011] In some implementations, the leaching process satisfies at least one of the following conditions: A. Control the liquid-to-solid ratio of the slurry to (2~10) g: 1 mL; B. The flow rate of the inert atmosphere introduced into the reaction vessel is 0.1 L / min to 10 L / min; C. Control the leaching temperature of the acid leaching reaction to be 30℃~90℃, and the leaching time to be 2h~24h; D. Control the particle size of nickel-iron alloy materials to -50 mesh; E. Inert atmosphere includes one or more of nitrogen and argon; F. Acids include one or more of hydrochloric acid, nitric acid, and hypochlorous acid.

[0012] In some implementations, the separation process satisfies at least one of the following conditions: G. The first extractant comprises a diluent and a compound having the following structural formula I: Formula I, Wherein, R1 is a nitrogen-containing heterocyclic group of C4-C20, R2 is selected from any one of hydrogen, C8C12 straight-chain or branched alkyl groups, and R3 is selected from any one of C8C12 straight-chain or branched alkyl groups; H. In the extraction process, the O / A volume ratio of the first extractant to the leachate is (2.5~5):1; I. The nickel concentration in the leachate should be controlled at 2 g / L to 30 g / L; J. The ferrous ion concentration in the leachate should be controlled at 80 g / L to 200 g / L. K. The pH of the leachate should be controlled between 0 and 1.5; it can be set to 0 to 1. L. The pH of the raffinate containing ferrous salts should be controlled at 0~2.1; M, The number of extraction stages in the extraction process is 3 to 9.

[0013] In some implementations, the resource recovery method satisfies at least one of the following conditions: N. In the nickel salt production process, the volume ratio of the nickel-loaded organic phase to the detergent O / A is controlled to be (5~30):1 during the washing process. In the nickel salt production process, the volume ratio of the nickel-loaded organic phase to the O / A of the stripping agent is controlled to be (10~50):1 during the back-extraction process. P. In the nickel salt production process, the washing treatment is grade 3 to 7. Q. In the nickel salt production process, the back-extraction treatment is at level 5 to 10. R. In the nickel salt production process, the pH of the nickel salt back-extraction solution is controlled at 0~3; S. In the nickel salt production process, the nickel concentration of the nickel salt back-extraction solution is controlled at 60g / L~120g / L; In the nickel salt production process, the washing agent used for the washing treatment is a nickel salt solution; U. In the nickel salt production process, the back-extraction agent used in the back-extraction treatment includes one or more of water, hydrochloric acid, and nitric acid; V. In the nickel salt purification process, the second extractant used for extraction and impurity removal includes one or more of P204, P507, and C272.

[0014] In some embodiments, the process of producing iron oxide red also includes purifying the raffinate containing ferrous salts before spray pyrolysis.

[0015] In some implementations, the process for producing iron oxide red satisfies at least one of the following conditions: W. The impurity removal and purification process uses one or more of iron powder and iron oxide scale. X. The pyrolysis temperature of spray pyrolysis treatment is 550℃~700℃; Y. The acidic tail gas produced by spray pyrolysis is recycled into the leaching process.

[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This paper illustrates a flowchart of a method for the resource recovery of nickel-iron alloys provided in an embodiment of this application. Detailed Implementation

[0019] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0020] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0021] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0022] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, optionally sequentially. For example, if a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if it is mentioned that the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0023] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" may also include or contain other components not listed, or may include only or contain the listed components.

[0024] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0025] It should be noted that the nickel-iron alloy in this application can be obtained by pyrometallurgical smelting, and the main elements in the nickel-iron alloy are iron and nickel, as well as one or more of cobalt, chromium, copper, manganese or zinc.

[0026] This application provides a method for the resource recovery of nickel-iron alloy, including: Leaching process: The nickel-iron alloy material is subjected to acid leaching reaction in an inert atmosphere, and after solid-liquid separation, a leachate containing nickel salt and ferrous salt is obtained. Separation process: The leachate is extracted with the first extractant to obtain a nickel-loaded organic phase and a raffinate containing ferrous salts; Nickel salt preparation process: The nickel-loaded organic phase is washed and back-extracted to obtain nickel salt back-extraction solution.

[0027] In this embodiment, during the leaching process, the nickel-iron alloy material undergoes an acid leaching reaction under an inert atmosphere, effectively inhibiting the oxidation of ferrous ions and suppressing the hydrolysis and precipitation of iron during leaching. This ensures that nickel and ferrous iron coexist stably in the leachate in ionic form, resulting in a leachate containing both nickel and ferrous salts after solid-liquid separation. In the separation process, selective extraction of the leachate using a first extractant preferentially and efficiently extracts nickel into the organic phase, achieving clean separation of nickel and ferrous iron. The extraction process yields a nickel-loaded organic phase and an extract phase rich in ferrous salts. Through the nickel salt preparation process, the nickel-loaded organic phase, after washing and back-extraction, yields a high-purity nickel salt back-extraction solution, providing high-quality raw materials for the preparation of high-end products such as battery-grade nickel salts. This achieves efficient separation of the nickel-iron alloy and high-value recovery of the nickel component.

[0028] It should be understood that ferrous salts remain in the raffinate in solution form. This raffinate, rich in ferrous salts, can serve as a high-value intermediate product, flexibly applicable to various subsequent scenarios (such as the preparation of iron oxide red), further enhancing the comprehensive utilization efficiency of nickel-iron alloys. Compared to traditional processes that require treatment of iron components through precipitation, oxidation, or secondary extraction, the embodiments of this application achieve nickel-iron separation in one step through selective nickel extraction, significantly reducing the consumption of chemicals such as neutralizing agents and oxidizing agents, significantly shortening the process flow, and reducing equipment investment and operating costs. At the same time, by protecting acid leaching and selective nickel extraction with an inert atmosphere, the introduction of impurities and the occurrence of side reactions are reduced from the source. The overall method ensures the quality of nickel products while possessing excellent economic efficiency and environmental friendliness.

[0029] In some embodiments, the leaching process includes: preparing a slurry from nickel-iron alloy material to obtain a slurry; placing the slurry in a reaction vessel, introducing an inert atmosphere and acid into the reaction vessel to carry out an acid leaching reaction, and obtaining a leachate containing nickel salt and ferrous salt after solid-liquid separation.

[0030] In this embodiment, the nickel-iron alloy material can be a powder. By pre-slurrying the nickel-iron alloy material and placing it in a reaction vessel, and then adding acid under an inert atmosphere, efficient dissolution of the nickel-iron alloy and stable retention of ferrous ions are achieved. The slurrying process ensures uniform dispersion of the material, which facilitates full contact between the acid and the alloy particles, thereby improving leaching efficiency. The inert atmosphere circulated in the reaction vessel and the flow rate controlled effectively isolates air, inhibits the oxidation of ferrous ions, and avoids the hydrolysis and precipitation of iron during the leaching process.

[0031] In some embodiments, during the leaching process, the liquid-to-solid ratio of the slurry is controlled at (2~10) g:1 mL. A liquid-to-solid ratio that is too low will cause the slurry to become viscous, hindering mass transfer and reducing leaching efficiency. It will also easily lead to excessively high local acid concentrations, triggering side reactions. A liquid-to-solid ratio that is too high will dilute the leachate, increasing the processing volume of subsequent processes and reducing equipment utilization. By controlling the liquid-to-solid ratio of the slurry within the range of (2~10) g:1 mL, it is possible to ensure sufficient leaching of the nickel-iron alloy while obtaining a suitable concentration of metal ions. This ensures effective and complete contact between the acid and the nickel-iron alloy material, and maintains the nickel and ferrous concentrations in the leachate within the ideal range for subsequent extraction processes. For example, the liquid-to-solid ratio of the slurry can be controlled as 2 g:1 mL, 3 g:1 mL, 4 g:1 mL, 5 g:1 mL, 6 g:1 mL, 7 g:1 mL, 8 g:1 mL, 9 g:1 mL, 10 g:1 mL, or any liquid-to-solid ratio within the range of (2~10) g:1 mL.

[0032] In some embodiments, the flow rate of the inert atmosphere into the reaction vessel is 0.1 L / min to 10 L / min. Controlling the gas flow rate within this range ensures that the air in the reaction space is replaced, avoiding excessive airflow that could lead to acid mist volatilization or temperature fluctuations. This achieves stable inert atmosphere protection at a lower cost, ensuring that ferrous ions in the leachate exist stably in the divalent form. For example, the flow rate of the inert atmosphere introduced into the reaction vessel can be 0.1 L / min, 1 L / min, 1.25 L / min, 1.5 L / min, 1.75 L / min, 2 L / min, 2.25 L / min, 2.5 L / min, 2.75 L / min, 3 L / min, 3.25 L / min, 3.5 L / min, 3.75 L / min, 4 L / min, 4.25 L / min, 4.5 L / min, 4.75 L / min, 5 L / min, 5.25 L / min, 5.5 L / min, 5.75 L / min, 6 L / min, 6.25 L / min, 6.5 L / min, 6.75 L / min, 7 L / min, 7.25 L / min, 7.5 L / min, 7.75 L / min, 8 L / min, 8.25 L / min, 8.5 L / min, 8.75 L / min. The flow rate can be any value within the range of L / min, 9 L / min, 9.25 L / min, 9.5 L / min, 9.75 L / min, 10 L / min, or 0 to 10 L / min.

[0033] In some embodiments, the leaching temperature of the acid leaching reaction is controlled at 30°C to 90°C, and the leaching time is controlled at 2 hours to 24 hours. When the leaching temperature is below 30°C, the reaction kinetics are slow; when the leaching temperature is above 90°C, acid mist volatilization, equipment corrosion, and energy consumption are exacerbated. Too short a leaching time leads to incomplete dissolution of the nickel-iron alloy material, while too long a time increases energy consumption and labor time, resulting in poor economic efficiency. Therefore, controlling the leaching temperature of the acid leaching reaction to 30°C to 90°C and the leaching time to 2 hours to 24 hours ensures complete dissolution of the nickel-iron alloy, high nickel and iron leaching rates, and controllable impurity content in the leaching solution, providing stable and high-quality raw materials for subsequent processes.

[0034] In this embodiment of the application, the leaching temperature of the acid leaching reaction is controlled to be 30℃~90℃, and the leaching time is 2h~24h. For example, the leaching temperature of the acid leaching reaction can be any leaching temperature within the range of 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or 30℃~90℃. The leaching time of the acid leaching reaction can be any leaching time within the range of 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, or 2h~24h.

[0035] In some embodiments, the particle size of the nickel-iron alloy material is controlled to be -50 mesh to increase the reaction surface area and accelerate the contact and reaction between the acid and the alloy. When the particle size of the nickel-iron alloy material is greater than 50 mesh, the acid solution cannot fully penetrate the interior of the particles, resulting in low leaching efficiency, incomplete leaching, and low metal recovery rate. Furthermore, unreacted nuclei are easily encapsulated by the product layer, further hindering the reaction. Crushing the material to below 50 mesh ensures that nickel and iron can be efficiently leached in a shorter time under mild leaching conditions, while reducing acid consumption and residue rate, and improving the overall economic efficiency of the process. It should be noted that, unless otherwise specified, the particle size "-XX" mesh in this application refers to particles that can pass through an "XX" mesh sieve. For example, particles with a particle size of -50 mesh refer to particles that can pass through a 50-mesh sieve.

[0036] In some embodiments, the inert atmosphere includes one or more of nitrogen and argon, which can effectively isolate oxygen during the leaching process and prevent the oxidation of ferrous ions.

[0037] In some embodiments, the acid solution includes one or more of hydrochloric acid, nitric acid, and hypochlorous acid. These acids, as leaching acids, can efficiently dissolve nickel-iron alloy materials.

[0038] In some embodiments, the first extractant used in the separation process includes a diluent and a compound having the following structural formula I: Formula I, In this formula, R1 is a C4-C20 nitrogen-containing heterocyclic group, such as any one of pyrrole, pyridinyl, quinolinyl, or isoquinolinyl; R2 is selected from any one of hydrogen, C8C12 straight-chain or branched alkyl groups, such as any one of hydrogen, octyl, isooctyl, decyl, isodecyl, or dodecyl; R3 is selected from any one of C8C12 straight-chain or branched alkyl groups, such as any one of octyl, isooctyl, decyl, isodecyl, or dodecyl. For example, the compounds having the structure shown in Formula I can specifically be N-octylquinoline-8-carboxamide, N-isooctylquinoline-8-carboxamide, N,N-di(octyl)quinoline-8-carboxamide, N,N-di(isooctyl)quinoline-8-carboxamide, N-octylisoquinoline-8-carboxamide, N-isooctylisoquinoline-8-carboxamide, etc., which can be purchased commercially or prepared by amide reaction. The diluent can be sulfonated kerosene, kerosene, or aliphatic hydrocarbon solvent oil. The compound of structural formula I above is mixed with the diluent to obtain the first extractant, which can efficiently and selectively extract nickel from a high-concentration ferrous environment. The nitrogen-containing heterocyclic group in this type of compound has coordination selectivity for nickel ions and can form a stable complex with nickel to enter the organic phase.

[0039] In some embodiments, the pH of the leachate is controlled between 0 and 1.5 during the separation process, and can be selected as 0 to 1. For example, the pH of the leachate during the separation process can be controlled to any pH value within the range of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, or 0 to 1.5. In the embodiments of this application, controlling the pH of the leachate before extraction to 0 to 1.5 allows ferrous ions to exist stably in their divalent form, making them less susceptible to oxidation or hydrolysis. Under these conditions, when using the first extractant for extraction, nickel has a higher extraction priority than iron, achieving selective extraction of nickel while essentially not extracting iron. If pH > 1.5, the nickel-iron separation effect is affected; if pH < 0, excessive acidity leads to degradation of the first extractant and a decrease in the nickel extraction rate.

[0040] In some embodiments, during the extraction process, the O / A volume ratio of the first extractant to the leachate is (2.5~5):1, which can ensure efficient nickel extraction while reasonably controlling equipment scale and reagent consumption. For example, during the extraction process, the O / A volume ratio of the first extractant to the leachate can be any O / A volume ratio among 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or (2.5~5):1.

[0041] In some embodiments, during the separation process, the nickel concentration of the leachate is controlled at 2 g / L to 30 g / L to ensure efficient recovery of the extraction process at an economical ratio and number of stages. It should be understood that if the nickel concentration of the leachate is too low, the processing volume needs to be increased or the circulation ratio increased to achieve the same processing capacity, leading to higher equipment investment and operating costs; if the nickel concentration of the leachate is too high, it may approach the saturation capacity of the first extractant, requiring an increase in the number of extraction stages or the O / A volume ratio, and is prone to the formation of a third phase or precipitation. In the separation process, the nickel concentration of the leaching solution is controlled at 2~30 g / L. For example, the nickel concentration of the leaching solution can be controlled at any nickel concentration value within the range of 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, 20 g / L, 21 g / L, 22 g / L, 23 g / L, 24 g / L, 25 g / L, 26 g / L, 27 g / L, 28 g / L, 29 g / L, 30 g / L, or 2~30 g / L.

[0042] In some embodiments, during the separation process, the ferrous ion concentration in the leachate is controlled at 80 g / L to 200 g / L. Within this concentration range, the selectivity of the first extractant for nickel is not affected by competition from ferrous ions, and the ferrous ions in the raffinate are retained in a pure form, which can be used for subsequent resource utilization (such as the preparation of iron oxide red). If the ferrous ion concentration is too low, it means that a large number of ferrous ions are oxidized, which is not conducive to improving the efficiency of nickel-iron separation. In the separation process, the ferrous ion concentration of the leachate is controlled at 80 g / L to 200 g / L. For example, the ferrous ion concentration of the leachate can be controlled at any concentration value within the range of 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, 125 g / L, 130 g / L, 135 g / L, 140 g / L, 145 g / L, 150 g / L, 155 g / L, 160 g / L, 165 g / L, 170 g / L, 175 g / L, 180 g / L, 185 g / L, 190 g / L, 195 g / L, 200 g / L, or 80 g / L to 200 g / L.

[0043] In some embodiments, during the separation process, the pH of the raffinate containing ferrous salts is controlled at 0 to 2.1, and it is isolated from air to prevent ferrous ions from being oxidized before subsequent processing.

[0044] In some embodiments, the extraction process in the separation step involves 3 to 9 extraction stages to ensure thorough separation of nickel and iron. For example, the extraction process can involve any number of extraction stages, such as 3, 4, 5, 6, 7, 8, 9, or 3 to 9.

[0045] In some embodiments, the resource recovery method for nickel-iron alloys further includes: Nickel salt purification process: A second extractant is used to extract and remove impurities from the nickel salt back-extraction solution, resulting in a purified nickel salt solution. By using a second extractant to remove impurities from the nickel salt back-extraction solution, impurities such as cobalt can be removed at a higher rate, resulting in a purified nickel salt solution with higher purity, thus meeting the purity requirements of raw materials in applications such as battery-grade nickel sulfate.

[0046] In some embodiments, the nickel salt purification process specifically includes: adjusting the pH value of the nickel salt back-extraction solution to 4.0-5.0; and using a second extractant to perform multi-stage countercurrent extraction of the pH-adjusted nickel salt back-extraction solution to obtain a cobalt salt solution and a purified nickel salt solution.

[0047] In the nickel salt purification process, by precisely controlling the pH value of the nickel salt back-extraction solution within the range of 4.0-5.0, the selective extraction capability of the second extractant for cobalt is maximized, while avoiding co-extraction loss of nickel. The fractionation multi-stage countercurrent extraction process achieves efficient and deep separation of cobalt and nickel through multi-stage countercurrent contact, significantly improving separation efficiency and product purity. Therefore, the embodiments of this application not only obtain a high-purity nickel solution that meets battery-grade nickel salt standards but also simultaneously recover cobalt salts, further enhancing the resource utilization value of nickel-iron alloys.

[0048] In this embodiment of the application, the pH value of the nickel salt back-extraction solution is adjusted to 4.0-5.0 in the nickel salt purification process. For example, the pH value of the nickel salt back-extraction solution can be adjusted to any pH value among 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0 or 4.0-5.0.

[0049] The fractionation multi-stage countercurrent extraction in this embodiment combines countercurrent extraction with fractionation and may include a saponification section, an extraction section, a washing section and a back-extraction section. During the extraction process, the organic phase and the aqueous phase flow in opposite directions and are in continuous contact. The two phases gradually approach equilibrium in multi-stage contact, and a high degree of separation can be achieved with fewer stages.

[0050] In some embodiments, the fractionation multi-stage countercurrent extraction sequentially includes: a saponification stage: pre-treating the second extractant with liquid alkali, wherein the O / A volume ratio of the second extractant to the liquid alkali is controlled at (20~30):1; an extraction stage: countercurrently extracting the nickel salt back-extraction solution with the pre-treated second extractant to obtain a cobalt-loaded organic phase and a purified nickel salt solution, wherein the O / A volume ratio of the pre-treated second extractant to the nickel salt back-extraction solution is controlled at (1.5~2.5):1; a washing stage: washing the cobalt-loaded organic phase with washing acid, wherein the O / A volume ratio of the cobalt-loaded organic phase to the washing acid is controlled at (8~12):1; and a back-extraction stage: back-extracting the washed cobalt-loaded organic phase with back-extraction acid, wherein the O / A volume ratio of the washed cobalt-loaded organic phase to the back-extraction acid is controlled at (8~12):1.

[0051] It is understandable that in the saponification section, the second extractant is pretreated with liquid alkali. By controlling the O / A volume ratio of the second extractant to liquid alkali at (20~30):1, the extraction capacity and phase separation performance of the second extractant can be improved. In the extraction section, the saponified second extractant is countercurrently extracted with a nickel salt back-extraction solution with a pH adjusted to 4.0-5.0. The volume ratio (O / A) of the organic phase to the aqueous phase in the extraction section is controlled at 2:1. Under these conditions, cobalt is selectively extracted into the organic phase, while nickel remains in the aqueous phase, resulting in a purified nickel salt solution. The washing and back-extraction sections use an O / A volume ratio of (8~12):1 for washing and back-extraction, respectively, effectively removing impurities entrained in the organic phase and achieving complete cobalt recovery. The synergistic effect of the O / A volume ratios in each section significantly improves the purity of the nickel salt product, meeting the stringent requirements of battery-grade nickel salts. Simultaneously, the byproduct cobalt salt solution further enhances the resource value of nickel-iron alloys.

[0052] In some embodiments, the second extractant includes one or more of P204, P507, and C272 to deeply remove impurities such as cobalt from the nickel salt back-extraction solution.

[0053] In some embodiments, during the nickel salt preparation process, the O / A volume ratio of the nickel-loaded organic phase to the detergent is controlled at (5~30):1 to effectively remove impurity ions entrained in the nickel-loaded organic phase while avoiding excessive backwashing loss of nickel. For example, the O / A volume ratio of the nickel-loaded organic phase to the detergent can be controlled at any O / A volume ratio within the range of 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, 27:1, 28:1, 29:1, 30:1, or (5~30):1.

[0054] In some embodiments, the washing process in the nickel salt production step is of 3 to 7 levels. For example, the washing process can be any number of levels from 3 to 9, such as 3, 4, 5, 6, 7, 8, 9.

[0055] In some embodiments, the detergent used in the washing process is a nickel salt solution, which helps to improve the purity of the nickel salt back-extraction solution.

[0056] In some embodiments, during the nickel salt production process, the O / A volume ratio of the nickel-loaded organic phase to the stripping agent is controlled to be (10~50):1 to improve the stripping efficiency and obtain a high-concentration nickel salt stripping solution.

[0057] In some embodiments, the back-extraction process in the nickel salt production step is of 5 to 10 stages. For example, the back-extraction process can be of any number of stages, such as 5, 6, 7, 8, 9, 10, or 5 to 10.

[0058] In some embodiments, the stripping agent used in the stripping process includes one or more of water, hydrochloric acid, and nitric acid.

[0059] In some embodiments, the pH of the nickel salt back-extraction solution obtained from the nickel salt preparation process is controlled at 0-3. Within this range, nickel ions can exist stably in a free state, facilitating direct use or further purification. For example, the pH of the nickel salt back-extraction solution obtained from the nickel salt preparation process can be controlled at any pH value within the range of 0, 0.5, 1.5, 2, 2.5, 3, or 0-3.

[0060] In some embodiments, the nickel concentration of the nickel salt back-extraction solution obtained in the nickel salt preparation process is controlled at 60 g / L to 120 g / L. If the concentration is too low, in order to obtain the same yield of purified nickel salt solution, it is necessary to increase the processing volume or extend the evaporation and concentration time, which is not conducive to the control of operating costs. If the concentration is too high, crystals will easily precipitate and block the pipelines and equipment.

[0061] In some embodiments, the resource recovery method for nickel-iron alloys further includes: The process for producing iron oxide red involves spraying the raffinate containing ferrous salts under an oxygen-containing atmosphere to obtain iron oxide red. During the spraying pyrolysis process, the raffinate containing ferrous salts is sprayed into fine droplets. Under high temperature and an oxygen-containing atmosphere, the ferrous salts undergo thermal decomposition and oxidation reactions, thereby generating iron oxide red. This process simultaneously produces high-purity nickel salts and iron oxide red using nickel-iron alloys, significantly improving resource utilization.

[0062] In some embodiments, the process of producing iron oxide red further includes purifying the raffinate containing ferrous salts before spray pyrolysis.

[0063] In some embodiments, the impurity removal and purification process uses one or more of iron powder and iron oxide scale to remove impurities such as chromium from the raffinate containing ferrous salts. After the impurity removal and purification process, the purity of the raffinate containing ferrous salts is significantly improved, thereby obtaining high-purity iron oxide red.

[0064] In some embodiments, the pyrolysis temperature of the spray pyrolysis treatment is 550℃~700℃. Within this temperature range, the ferrous salt can be fully decomposed and oxidized to obtain a crystalline iron oxide red product with a pure color. The pyrolysis temperature of the spray pyrolysis treatment is 550℃~700℃. For example, the pyrolysis temperature of the spray pyrolysis treatment can be any temperature within the range of 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, or 550℃~700℃.

[0065] In some embodiments, the acidic tail gas produced by spray pyrolysis is recycled into the leaching process. Recycling the acidic tail gas (e.g., HCl gas) produced by spray pyrolysis into the leaching process allows for the reuse of the acid and heat generated by pyrolysis, reducing acid and energy consumption, avoiding environmental pressure caused by the emission of acidic gases, and improving resource utilization.

[0066] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all reagents and raw materials used in the embodiments are commercially available or synthesized by conventional methods, and the instruments used in the embodiments are also commercially available.

[0067] Example 1 A method for the resource recovery of nickel-iron alloy is provided, comprising: Leaching process: 7 kg of nickel-iron alloy material with a particle size of -50 mesh is provided for pulping. The liquid-to-solid ratio of the slurry is controlled at 4 g:1 mL. The slurry is placed in a reaction vessel, and helium and hydrochloric acid are introduced into the reaction vessel for acid leaching. After solid-liquid separation, a leachate containing nickel salt and ferrous salt is obtained. The initial hydrogen ion concentration of the acid leaching reaction is 8 mol / L, the leaching temperature is 60℃, the leaching time is 15 h, and the flow rate of helium introduced into the reaction vessel is 5 L / min. Separation process: The pH of the leachate is controlled at 0.5. The leachate is subjected to hand-shaking extraction using the first extractant to obtain a nickel-loaded organic phase and a raffinate containing ferrous salts. The pH of the raffinate containing ferrous salts is 2.1. The first extractant is prepared by mass percentage of 20% N-octylisoquinoline 8-formamide and 80% kerosene. The O / A volume ratio of the first extractant to the leachate is 3:1. Nickel salt preparation process: The nickel-loaded organic phase is washed and manually back-extracted. After manual back-extraction, the aqueous phase changes from colorless to dark green, yielding a nickel salt back-extraction solution. The pH of the nickel salt back-extraction solution is controlled at 1.6. In the washing process, the O / A volume ratio of the nickel-loaded organic phase to the detergent is controlled at 30:1, and nickel chloride with 30 g / L Ni is used as the detergent. In the back-extraction process, the O / A volume ratio of the nickel-loaded organic phase to the back-extraction agent is controlled at 25:1, and water is used as the back-extraction agent.

[0068] Example 2 A method for the resource recovery of nickel-iron alloy is provided, comprising: Leaching process: 20 kg of nickel-iron alloy material with a particle size of -50 mesh is provided for pulping. The liquid-to-solid ratio of the slurry is controlled at 4.5 g: 1 mL. The slurry is placed in a reaction vessel, and helium and hydrochloric acid are introduced into the reaction vessel for acid leaching. After solid-liquid separation, a leachate containing nickel salt and ferrous salt is obtained. The initial hydrogen ion concentration of the acid leaching reaction is 8.1 mol / L, the leaching temperature is 60℃, the leaching time is 15.5 h, and the flow rate of helium introduced into the reaction vessel is 5 L / min. Separation process: The pH of the leachate is controlled at 0.7. The leachate is subjected to a 7-stage countercurrent extraction process using the first extractant to obtain a nickel-loaded organic phase and a raffinate containing ferrous salts. The pH of the raffinate containing ferrous salts is 1.8. The first extractant is prepared by mass percentage of 20% N,N-bis(octyl)quinoline 8-formamide and 80% kerosene. The O / A volume ratio of the first extractant to the leachate is 3:1. Nickel salt preparation process: The nickel-loaded organic phase is mixed with a nickel chloride solution containing 30 g / L Ni at an O / A volume ratio of 30:1 and washed. Then, pure water is used as the back-extraction agent, and the O / A volume ratio of the nickel-loaded organic phase to the back-extraction agent is 40:1 for back-extraction treatment to obtain nickel salt back-extraction solution. The pH of the nickel salt back-extraction solution is controlled at 1.7. Nickel salt purification process: The pH of the nickel salt back-extraction solution is adjusted to 4.5 using liquid alkali. A second extractant is then used to perform multi-stage countercurrent fractionation extraction on the pH-adjusted nickel salt back-extraction solution to obtain a cobalt salt solution and a purified nickel salt solution. The multi-stage countercurrent fractionation extraction is performed in the following order: saponification stage, extraction stage, washing stage, and back-extraction stage. The saponification stage consists of two stages. The second extractant is prepared with a ratio of 30% P507 extractant and 70% solvent oil by mass percentage, and the alkali used for saponification is the solute. The extraction stage uses a 32% (w / w) liquid alkali solution with an O / A volume ratio of 25:1 for the second extractant to the liquid alkali. The extraction section is a six-stage extraction process with an O / A volume ratio of 2:1 for the second extractant to the nickel salt back-extraction solution. The washing stage is a four-stage washing process with 1 mol / L hydrochloric acid as the washing acid, and an O / A volume ratio of 10:1 for the cobalt-loaded organic phase to the washing acid. The back-extraction stage is a four-stage back-extraction process with 4 mol / L hydrochloric acid as the back-extraction acid, and an O / A volume ratio of 10:1 for the cobalt-loaded organic phase to the back-extraction acid after washing. Iron oxide red preparation process: The pH of the raffinate containing ferrous salt is adjusted to 3 using iron sheet. After reacting for 1 hour, it is filtered to obtain a purified raffinate containing ferrous salt. Then, it is sprayed pyrolysis at 600℃ in an air atmosphere to obtain iron oxide red. The acidic hydrogen chloride tail gas produced by the spray pyrolysis is recycled to the leaching process.

[0069] Example 3 A method for the resource recovery of nickel-iron alloy is provided, comprising: Leaching process: Same as in Example 1; Separation process: The extractant and extraction conditions are the same as in Example 1, except that the pH of the leachate is controlled to be 2.5 using a nickel-iron alloy.

[0070] Comparative Example 1 A method for the resource recovery of nickel-iron alloy is provided, comprising: Leaching process: It is basically the same as in Example 3, except that helium gas is not introduced for protection and a certain amount of oxygen is present in the leaching environment.

[0071] Separation process: Same as in Example 3.

[0072] It should be noted that the composition data of the nickel-iron alloy materials in the above embodiments are shown in Table 1: Table 1. Statistical Table of Main Components of Nickel-Iron Alloy Materials The composition of the leachate obtained in the leaching process of Example 1, the single-stage extraction results of the separation process, and the back-extraction parameters of the nickel salt production process were statistically analyzed, and the results are shown in Tables 2-4 below.

[0073] Table 2. Statistical table of leachate composition obtained from the leaching process in Example 1 Table 3. Statistical table of single-stage extraction results in the separation process of Example 1 Table 4. Statistical Table of Back-extraction Processing Parameters in Nickel Salt Preparation Process of Example 1 It should be noted that the extract in Tables 2 and 3 refers to the leachate before extraction in the separation process. The extract is derived from the leachate. Due to the long storage time and testing, the composition of the extract is slightly different from that of the leachate.

[0074] The components of the leachate obtained in the leaching process of Example 2, the components of the nickel salt back-extraction solution obtained in the nickel salt preparation process, the components of the cobalt salt solution obtained in the nickel salt purification process, the components of the raffinate containing ferrous salt in the iron oxide red preparation process after purification, and the components of the iron oxide red obtained in the iron oxide red preparation process were statistically analyzed, and the results are shown in Tables 5-9 below.

[0075] Table 5. Statistical table of leachate composition obtained from the leaching process in Example 2 Table 6. Statistical table of composition of nickel salt back-extraction solution obtained from the nickel salt preparation process in Example 2. Table 7. Statistical table of cobalt salt solution composition obtained from nickel salt purification process in Example 2 Table 8. Statistical table of components of the raffinate containing ferrous salts after purification treatment in the iron oxide red preparation process of Example 2. Table 9. Statistical table of iron oxide red composition obtained in the iron oxide red preparation process of Example 2. The results of single-stage extraction in the separation process of Example 3 were statistically analyzed, and the results are shown in Table 10 below.

[0076] Table 10. Statistical table of aqueous phase composition obtained from single-stage extraction in the separation process of Example 3. The results of single-stage extraction in the separation process of Comparative Example 1 were statistically analyzed, and the results are shown in Table 11 below.

[0077] Table 11. Statistical table of aqueous phase composition obtained from single-stage extraction in the separation process of Comparative Example 1 In summary, the resource utilization method for nickel-iron alloys provided in this application embodiment can fully realize the high-value utilization of nickel and iron on a relatively economical basis, and the quality of the obtained nickel salts and iron oxide red can reach a high standard.

[0078] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for the resource utilization of nickel-iron alloy, characterized in that, include: Leaching process: The nickel-iron alloy material is subjected to acid leaching reaction in an inert atmosphere, and after solid-liquid separation, a leachate containing nickel salt and ferrous salt is obtained. Separation process: The leachate is extracted with a first extractant to obtain a nickel-loaded organic phase and a raffinate containing ferrous salts; Nickel salt preparation process: The organic phase loaded with nickel is washed and back-extracted to obtain nickel salt back-extraction solution.

2. The method for resource recovery of nickel-iron alloy according to claim 1, characterized in that, Also includes: Nickel salt purification process: The nickel salt back-extraction solution is extracted and impurities are removed using a second extractant to obtain a purified nickel salt solution; And / or, Iron oxide red preparation process: The raffinate containing ferrous salt is subjected to spray pyrolysis treatment under an oxygen-containing atmosphere to obtain iron oxide red.

3. The method for resource recovery of nickel-iron alloy according to claim 2, characterized in that, The nickel salt purification process specifically includes: The pH of the nickel salt back-extraction solution is adjusted to 4.0-5.0; The pH-adjusted nickel salt back-extraction solution was subjected to fractionation and multi-stage countercurrent extraction using a second extractant to obtain a cobalt salt solution and a purified nickel salt solution.

4. The resource recovery method for nickel-iron alloy according to claim 3, wherein the fractionation multi-stage countercurrent extraction comprises: Saponification section: The second extractant is pretreated with liquid alkali for saponification, wherein the O / A volume ratio of the second extractant to the liquid alkali is controlled to be (20~30):1; Extraction section: The nickel salt back-extraction solution is countercurrently extracted using a second extractant after saponification pretreatment to obtain a cobalt-loaded organic phase and a purified nickel salt solution, wherein the O / A volume ratio of the second extractant after saponification pretreatment to the nickel salt back-extraction solution is controlled to be (1.5~2.5):1; Washing section: The organic phase of the cobalt-loaded organic phase is washed with washing acid, wherein the O / A volume ratio of the organic phase of the cobalt-loaded organic phase to the washing acid is controlled to be (8~12):1; Back-extraction section: Back-extraction acid is used to back-extract the cobalt-loaded organic phase after washing, wherein the O / A volume ratio of the washed cobalt-loaded organic phase to the back-extraction acid is controlled to be (8~12):

1.

5. The method for resource recovery of nickel-iron alloy according to any one of claims 1 to 4, characterized in that, The leaching process includes: The nickel-iron alloy material is slurried to obtain a mineral slurry; The slurry is placed in a reaction vessel, and an inert atmosphere and acid solution are introduced into the reaction vessel to carry out an acid leaching reaction. After solid-liquid separation, a leachate containing nickel salt and ferrous salt is obtained.

6. The method for resource recovery of nickel-iron alloy according to claim 5, characterized in that, The leaching process satisfies at least one of the following conditions: A. Control the liquid-to-solid ratio of the slurry to (2~10) g: 1 mL; B. The flow rate of the inert atmosphere introduced into the reaction vessel is 0.1 L / min to 10 L / min; C. The leaching temperature of the acid leaching reaction is controlled at 30℃~90℃, and the leaching time is 2h~24h; D. Control the particle size of the nickel-iron alloy material to -50 mesh; E. The inert atmosphere includes one or more of nitrogen and argon; F. The acid solution includes one or more of hydrochloric acid, nitric acid, and hypochlorous acid.

7. The method for resource recovery of nickel-iron alloy according to any one of claims 1 to 4, characterized in that, The separation process satisfies at least one of the following conditions: G. The first extractant comprises a diluent and a compound having the following structural formula I: Formula I, Wherein, R1 is a nitrogen-containing heterocyclic group of C4-C20, R2 is selected from any one of hydrogen, C8-C12 straight-chain or branched alkyl groups, and R3 is selected from any one of C8-C12 straight-chain or branched alkyl groups; H. In the extraction process, the O / A volume ratio of the first extractant to the leachate is (2.5~5):1; I. The nickel concentration of the leaching solution is controlled to be 2 g / L ~ 30 g / L; J. The ferrous ion concentration of the leachate is controlled to be 80 g / L ~ 200 g / L; K. The pH of the leachate is controlled to be 0~1.5; optionally, it is 0~1. L. The pH of the raffinate containing ferrous salts is controlled to be 0~2.1; M. The number of extraction stages in the extraction process is 3 to 9.

8. The method for resource recovery of nickel-iron alloy according to claim 2, characterized in that, The resource recovery method satisfies at least one of the following conditions: N. In the nickel salt production process, the washing process controls the O / A volume ratio of the nickel-loaded organic phase and the detergent to be (5~30):

1. O. In the nickel salt production process, the back-extraction process controls the volume ratio of the nickel-loaded organic phase to the back-extractant O / A to be (10~50):1; P. In the nickel salt production process, the washing treatment is of level 3 to 7. Q. In the nickel salt production process, the back-extraction treatment is at level 5 to 10. R. In the nickel salt production process, the pH of the nickel salt back-extraction solution is controlled to be 0~3; S. In the nickel salt preparation process, the nickel concentration of the nickel salt back-extraction solution is controlled at 60 g / L to 120 g / L; T. In the nickel salt production process, the washing treatment uses a nickel salt solution as the washing agent; U. In the nickel salt production process, the back-extraction agent used in the back-extraction treatment includes one or more of water, hydrochloric acid, and nitric acid; V. In the nickel salt purification process, the second extractant used in the extraction and impurity removal treatment includes one or more of P204, P507, and C272.

9. The method for resource recovery of nickel-iron alloy according to any one of claims 2 to 4, characterized in that, The process for producing iron oxide red also includes purifying the raffinate containing ferrous salts before spray pyrolysis.

10. The method for resource recovery of nickel-iron alloy according to claim 9, characterized in that, The iron oxide red preparation process satisfies at least one of the following conditions: W. The impurity removal and purification process uses one or more of iron powder and iron oxide scale. X. The pyrolysis temperature of the spray pyrolysis treatment is 550℃~700℃; Y. The acidic tail gas produced by the spray pyrolysis treatment is recycled into the leaching process.

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