Method for recovering valuable metals from waste nickel-based superalloys

Abstract

The application provides a method for recycling valuable metals in waste nickel-based superalloy. The method comprises the following steps: sequentially performing alkaline degreasing treatment and acid deoxidation layer treatment on the waste nickel-based superalloy to obtain a to-be-treated material; mixing the to-be-treated material and a molten Mg-M alloy to perform an extraction reaction, and separating a nickel-cobalt eutectic body and an alloy residue after the reaction; M in the molten Mg-M alloy is an auxiliary metal; performing vacuum distillation on the nickel-cobalt eutectic body, and then performing acid leaching on the separated crude nickel-cobalt powder to obtain an acid leaching solution; purifying the acid leaching solution through a chelating type composite membrane to obtain a purified nickel-cobalt solution; performing stripping treatment on the purified nickel-cobalt solution to obtain a stripping solution, and performing evaporation concentration and reduction reaction on the stripping solution to obtain product-grade nickel-cobalt powder. The method provided by the application improves the recycling efficiency and product purity of valuable metals, realizes efficient recycling of nickel-cobalt resources in waste nickel-based superalloy, is low in cost, and is environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of recycling technology for waste high-temperature alloys, specifically relating to a method for recycling valuable metals from waste nickel-based high-temperature alloys. Background Technology

[0002] Nickel-based superalloys are an important class of materials with nickel as the base metal, exhibiting excellent strength, oxidation resistance, and resistance to gas corrosion within the temperature range of 650-1000℃. In addition to the main metals such as nickel, cobalt, and chromium, nickel-based superalloys also contain a large amount of precious and rare metals such as rhenium, tungsten, tantalum, niobium, and hafnium. Therefore, recovering valuable metals from scrap nickel-based superalloys has significant economic and environmental benefits.

[0003] Currently, the main methods for recycling valuable metals from high-temperature alloy scrap include pyrometallurgy, hydrometallurgy, and electrochemical methods. The main technologies for recovering nickel, cobalt, and other metals from nickel-based high-temperature alloy scrap include electrochemical dissolution with chloride solution, hot acid leaching, forced-air acid leaching, electrochemical dissolution, pressurized acid leaching or chloride leaching, and chemical dissolution with a mixture of sulfuric acid and nitric acid. Pyrometallurgy typically employs surface treatment, vacuum oxygen decarburization (VOD), special slag systems for inclusion removal, and high-vacuum purification, combined with equipment such as vacuum induction furnaces and electroslag furnaces for regeneration.

[0004] However, existing recycling methods generally suffer from technical problems such as low efficiency in recovering valuable metals and insufficient product purity, making it difficult to achieve efficient, low-cost, and high-purity industrial recycling.

[0005] Existing technologies suffer from problems such as low recycling efficiency and low recycling purity.

[0006] Therefore, improving the recycling efficiency and purity of valuable metals in scrap nickel-based superalloys is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a method for recovering valuable metals from waste nickel-based superalloys. The invention first subjectes the waste nickel-based superalloy to alkaline degreasing and acidic deoxidation treatments sequentially to remove surface interfering substances, thereby improving the contact between the molten Mg-M alloy and nickel-cobalt and enhancing extraction efficiency. Secondly, a chelating composite membrane is introduced to purify the acid leaching solution, selectively retaining Ni... 2+ Co 2+ This process effectively removes any remaining metallic impurities, further improving the purity of the recovered nickel and cobalt. Finally, through back-extraction, evaporation concentration, and reduction, product-grade nickel and cobalt powder is obtained. This recovery method significantly improves the recovery efficiency and product purity of valuable metals, achieving efficient and high-purity recovery of nickel and cobalt resources from waste nickel-based superalloys. The process is short, simple to operate, and has good economic and environmental benefits.

[0008] To achieve this objective, the present invention employs the following technical solution: This invention provides a method for recycling valuable metals from waste nickel-based high-temperature alloys, the recycling method comprising the following steps: Waste nickel-based superalloys were subjected to alkaline degreasing and acidic deoxidation treatments in sequence to obtain the material to be treated.

[0009] The material to be processed is mixed with molten Mg-M alloy and subjected to an extraction reaction. After the reaction, a nickel-cobalt eutectic and an alloy residue are separated. M in the molten Mg-M alloy is an auxiliary metal.

[0010] The nickel-cobalt eutectic is subjected to vacuum distillation, and the separated crude nickel-cobalt powder is then acid-leached to obtain an acid leaching solution. The acid leaching solution is then purified using a chelating composite membrane to obtain a purified nickel-cobalt solution.

[0011] The purified nickel-cobalt solution was back-extracted, and the resulting back-extract was concentrated by evaporation and reduced to obtain product-grade nickel-cobalt powder.

[0012] This invention first subjectes waste nickel-based superalloys to alkaline degreasing and acidic deoxidation treatments to remove surface interfering substances, thereby improving the contact between the molten Mg-M alloy and nickel-cobalt and enhancing extraction efficiency. Secondly, a chelating composite membrane is introduced to purify the acid leaching solution, selectively retaining Ni... 2+ Co 2+ This process effectively removes any remaining metallic impurities, further improving the purity of the recovered nickel and cobalt. Finally, through back-extraction, evaporation concentration, and reduction, product-grade nickel and cobalt powder is obtained. This recovery method significantly improves the recovery efficiency and product purity of valuable metals, achieving efficient and high-purity recovery of nickel and cobalt resources from waste nickel-based superalloys. The process is short, simple to operate, and has good economic and environmental benefits.

[0013] This invention uses molten Mg-M alloy as an extractant. Under certain conditions, it can selectively dissolve Ni and Co in waste nickel-based superalloys, extracting them from the waste nickel-based superalloys to form a nickel-cobalt eutectic. Meanwhile, impurities in the alloy that are difficult to dissolve by Mg-M alloy (such as Cr, W, Al, Ti, etc.) remain in the solid phase, completing the initial separation of nickel and cobalt from most impurities. The extraction principle is that the thermodynamic compatibility (solubility) of molten Mg-M alloy with Ni and Co is much higher than its compatibility with impurities such as Cr, W, Al, Ti, etc.

[0014] Preferably, the particle size D50 of the waste nickel-based superalloy is 0.1-5mm, for example, it can be 0.1mm, 0.5mm, 1mm, 3mm or 5mm, etc.

[0015] In this invention, the suitable particle size D50 of the waste nickel-based superalloy has a larger specific surface area, which helps to quickly and fully remove oil and oxide scale during subsequent alkaline degreasing and acidic deoxidation treatments. At the same time, it can ensure the efficiency of contact reaction with molten Mg-M alloy and improve the extraction rate of valuable metals.

[0016] Preferably, the alkaline solution used in the alkaline degreasing process includes any one or a combination of at least two of sodium hydroxide solution, sodium carbonate solution, or sodium phosphate solution.

[0017] Preferably, the temperature of the alkaline degreasing treatment is 45-85℃, for example, 45℃, 50℃, 60℃, 75℃ or 85℃, and the treatment time is 10-60min, for example, 10min, 20min, 30min, 45min or 60min.

[0018] This invention performs alkaline degreasing treatment at a suitable temperature, which not only meets the basic requirements but also avoids excessively high temperatures that could cause the alkaline solution to evaporate or a new oxide film to form on the alloy surface, thereby ensuring the uniformity of subsequent pickling processes.

[0019] Preferably, the acid solution used in the acidic deoxidation layer treatment includes any one or a combination of at least two of hydrochloric acid solution, sulfuric acid solution, or nitric acid solution.

[0020] Preferably, the temperature of the acidic deoxidation layer treatment is 30-60℃, for example, 30℃, 35℃, 45℃, 55℃ or 60℃, and the treatment time is 10-30min, for example, 10min, 15min, 20min, 25min or 30min.

[0021] This invention performs acidic deoxidation treatment at a suitable temperature, which not only meets the basic requirements but also activates the alloy surface. The suitable temperature can accelerate the pickling rate, shorten the treatment time, and prevent excessive corrosion of the metal or excessive volatilization of the acid caused by excessive temperature.

[0022] Preferably, the auxiliary metal includes any one or a combination of at least two of Zn, Sn, or Pb.

[0023] In the molten Mg-M alloy used in this invention, any one or a combination of at least two of Zn, Sn, or Pb is used as an auxiliary metal M, which acts as a physical modifier. It is mainly used to improve the physical properties of the extraction medium (such as melting point, viscosity, and fluidity), so that valuable metals such as Ni and Co dissolve from the alloy phase to form a nickel-cobalt eutectic, while insoluble impurity elements (such as Cr, Mo, W, etc.) remain in the alloy residue, thereby achieving efficient separation.

[0024] Preferably, the molten Mg-M alloy has a Mg molar percentage content of 45%-75%, for example, it can be 45%, 55%, 65% or 75%.

[0025] In the molten Mg-M alloy used in this invention, the molar percentage of Mg is within a suitable range, which can ensure that the molten Mg-M alloy has a low melting point and good fluidity, while maintaining a strong extraction ability for Ni and Co.

[0026] Preferably, the mass ratio of the material to be processed to the molten Mg-M alloy is 1:(3-10), for example, it can be 1:3, 1:4, 1:6, 1:8 or 1:10, etc.

[0027] In the extraction process, this invention limits the mass ratio of the material to be treated and the molten Mg-M alloy to the above range, which can ensure that there is enough molten Mg-M alloy to fully contact the waste nickel-based superalloy and dissolve valuable metals such as Ni and Co.

[0028] Preferably, the temperature of the extraction reaction is 700-1000℃, for example, 700℃, 750℃, 800℃, 900℃ or 1000℃.

[0029] Preferably, the extraction reaction time is 3-24 hours, for example, 3 hours, 6 hours, 12 hours, 18 hours or 24 hours.

[0030] Preferably, the atmosphere for the extraction reaction is an inert atmosphere. For example, it may be a nitrogen atmosphere or an argon atmosphere.

[0031] Preferably, the separation method is membrane filtration; during the membrane filtration process, the membrane used is a high-temperature resistant ceramic membrane.

[0032] It should be noted that high-temperature resistant ceramic membranes are porous separation membranes prepared using ceramic materials such as alumina, zirconium oxide, or silicon carbide as the matrix. They can be made in-house or purchased directly. For example, commercially available ceramic membrane products can be selected, such as alumina ceramic membranes or silicon carbide ceramic membranes from Jiangsu Jiuwu High-Tech Co., Ltd., or porous ceramic membranes or silicon carbide ceramic membranes from Shandong Bona Biotechnology Group Co., Ltd.

[0033] This invention employs membrane filtration as a separation method, which can quickly separate molten eutectic and residue, shortening the separation and filtration time.

[0034] Preferably, the vacuum distillation includes a first-stage distillation and a second-stage distillation performed sequentially.

[0035] The temperature of the first-stage distillation is 1100-1300℃, for example, 1100℃, 1150℃, 1200℃, 1250℃ or 1300℃, etc., and the vacuum degree is 1-10Pa, for example, 1Pa, 2Pa, 4Pa, 7Pa or 10Pa, etc.

[0036] The secondary distillation temperature is 1500-1800℃, for example, 1500℃, 1600℃, 1700℃, 1750℃, or 1800℃, and the vacuum degree is 1×10⁻⁶. -2 -1×10 -1 Pa, for example, could be 1×10 -2 Pa, 3×10 -2 Pa, 5×10 -2 Pa, 8×10 -2 Pa or 1×10 -1 Pa, etc.

[0037] This invention employs a multi-stage heating and depressurization vacuum distillation method, which not only utilizes the boiling point difference between Mg and M metals to achieve precise separation and improve the purity of the recovered Mg and M metals, but also further removes residual trace impurity metals (such as Fe, Cu, etc.) through secondary distillation, thereby further improving the purity of nickel and cobalt in the obtained crude nickel-cobalt powder. At the same time, the recovered Mg and M metals can be returned to the extraction step for recycling.

[0038] Preferably, the acid solution used in the acid leaching process includes any one or a combination of at least two of sulfuric acid solution, hydrochloric acid solution, or nitric acid solution.

[0039] Preferably, in the chelating composite membrane, the functional groups that retain nickel and cobalt ions include aminophosphonic acid groups or iminodiacetic acid groups.

[0040] It should be noted that the chelating composite membrane mainly consists of a supporting base membrane (such as a polyethylene membrane) and a chelating functional layer (containing the aforementioned functional groups for retaining nickel and cobalt ions). It can be made in-house or purchased directly. For example, commercially available Tulsimer® CH-90Na chelating resin (from Kehaisi Technology Co., Ltd.), Tulsimer® CH-27 phosphonic acid composite membrane (from Kehaisi Technology Co., Ltd.), or D418 chelating resin (from Kerry Environmental Protection Technology Co., Ltd.) can be used.

[0041] This invention employs a chelating composite membrane with functional groups including aminophosphonic acid groups or imine diacetic acid groups to purify the acid leaching solution, utilizing these functional groups to purify Ni. 2+ and Co 2+Its high affinity and selective coordination enable it to preferentially chelate and adsorb nickel and cobalt ions under acidic conditions, while making it difficult for impurity metal ions in the acid leaching solution to be retained and discharged with the filtrate, thereby achieving efficient separation and enrichment of nickel and cobalt.

[0042] Preferably, the back-extraction reagent used in the back-extraction process includes any one or a combination of at least two of sulfuric acid solution, hydrochloric acid solution, or ammonium acetate solution.

[0043] Preferably, the temperature of the reduction reaction is 400-800℃, for example, 400℃, 500℃, 600℃, 700℃ or 800℃, and the time is 1-4h, for example, 1h, 2h, 2.5h, 3h or 4h.

[0044] Preferably, the recycling method includes the following steps: (1) Pretreatment: The waste nickel-based superalloy is crushed to a particle size D50 of 0.1-5 mm, and then immersed in an alkaline solution with a concentration of 0.5-2 mol / L (e.g., 0.5 mol / L, 0.8 mol / L, 1.0 mol / L, 1.5 mol / L, or 2.0 mol / L, etc.) for alkaline degreasing treatment at 45-85℃ for 10-60 min. Then, it is immersed in an acidic solution with a concentration of 0.5-3 mol / L (e.g., 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, or 3.0 mol / L, etc.) for acidic deoxidation treatment at 30-60℃ for 10-30 min. After the treatment, it is removed and vacuum dried to obtain the material to be treated.

[0045] (2) Extraction: The material to be treated and the molten Mg-M alloy are mixed at a mass ratio of 1:(3-10), and then an extraction reaction is carried out at 700-1000℃ under an inert atmosphere for 3-24 hours with stirring during the reaction. After the reaction, the mixture is filtered through a high-temperature resistant ceramic membrane to separate the nickel-cobalt eutectic and alloy residue. In the molten Mg-M alloy, M is an auxiliary metal, which includes any one or a combination of at least two of Zn, Al, or Ca. The molar percentage of Mg in the molten Mg-M alloy is 45-75%. The pore size of the high-temperature resistant ceramic membrane is 0.1-10 μm (e.g., 0.1 μm, 0.5 μm, 1 μm, 5 μm, or 10 μm, etc.).

[0046] (3) Vacuum distillation: The nickel-cobalt eutectic was subjected to primary distillation to recover Mg metal under vacuum conditions of 1-10 Pa and temperature of 1100-1300 °C, and then the Mg metal was recovered under vacuum conditions of 1×10 Pa. -2-1×10 -1 The M metal was recovered by two-stage distillation under conditions of Pa and temperature of 1500-1800℃ to obtain crude nickel-cobalt powder.

[0047] (4) Acid leaching and membrane filtration: The crude nickel-cobalt powder is immersed in an acid solution with a concentration of 1-4 mol / L (e.g., 1 mol / L, 1.5 mol / L, 2 mol / L, 3 mol / L, or 4 mol / L) for acid leaching treatment to obtain an acid leaching solution containing nickel and cobalt.

[0048] The acid leaching solution is purified by a chelating composite membrane to obtain a purified nickel-cobalt solution; wherein, the functional groups in the chelating composite membrane that retain nickel and cobalt ions include aminophosphonic acid groups or imine diacetic acid groups.

[0049] (5) Post-processing: The purified nickel-cobalt solution is back-extracted using a back-extraction reagent to obtain a nickel-cobalt-containing back-extraction solution; wherein the back-extraction reagent includes any one or a combination of at least two of sulfuric acid solution, hydrochloric acid solution, or ammonium acetate solution.

[0050] The back-extraction solution is evaporated and concentrated, and then a reduction reaction is carried out in a reducing atmosphere at 400-800℃ for 1-4 hours to obtain product-grade nickel-cobalt powder; wherein the reducing gas in the reducing atmosphere includes a hydrogen atmosphere.

[0051] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0052] Compared with the prior art, the present invention has the following beneficial effects: This invention first subjectes waste nickel-based superalloys to alkaline degreasing and acidic deoxidation treatments to remove surface interfering substances, thereby improving the contact between the molten Mg-M alloy and nickel-cobalt and enhancing extraction efficiency. Secondly, a chelating composite membrane is introduced to purify the acid leaching solution, selectively retaining Ni... 2+ Co 2+ This process effectively removes any remaining metallic impurities, further improving the purity of the recovered nickel and cobalt. Finally, through back-extraction, evaporation concentration, and reduction, product-grade nickel and cobalt powder is obtained. This recovery method significantly improves the recovery efficiency and product purity of valuable metals, achieving efficient and high-purity recovery of nickel and cobalt resources from waste nickel-based superalloys. The process is short, simple to operate, and has good economic and environmental benefits. Detailed Implementation

[0053] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0054] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0055] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0056] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0057] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0058] It should be noted that the main components and their contents of the waste nickel-based superalloys mentioned in the following embodiments are shown in Table 1 below.

[0059] Table 1 Example 1 This embodiment provides a method for recycling valuable metals from waste nickel-based superalloys, the recycling method comprising the following steps: (1) Pretreatment: The waste nickel-based superalloy was crushed to a particle size D50 of 2.5 mm, then immersed in a 1 mol / L sodium hydroxide solution for alkaline degreasing at 65°C for 35 min, and then immersed in a 2 mol / L hydrochloric acid solution for acidic deoxidation at 45°C for 20 min. After the treatment, the material was removed and vacuum dried to obtain the material to be treated.

[0060] (2) Extraction: The material to be treated and the molten Mg-M alloy were mixed at a mass ratio of 1:6, and then an extraction reaction was carried out at 850°C under a nitrogen atmosphere for 14 hours with stirring during the reaction. After the reaction, the mixture was filtered through a high-temperature resistant ceramic membrane to separate the nickel-cobalt eutectic and alloy residue. In the molten Mg-M alloy, M is Zn; the molar percentage of Mg in the molten Mg-M alloy is 60%; the pore size of the high-temperature resistant ceramic membrane is 5μm, and the material is alumina (alumina ceramic membrane from Jiangsu Jiuwu High-Tech Co., Ltd.).

[0061] (3) Vacuum distillation: The nickel-cobalt eutectic was subjected to primary distillation to recover Mg metal under a vacuum of 5 Pa and a temperature of 1200 °C, and then subjected to a vacuum of 5 × 10⁻⁶ Pa. -2 The M metal was recovered by two-stage distillation under the conditions of Pa and temperature of 1650℃ to obtain crude nickel-cobalt powder.

[0062] (4) Acid leaching and membrane filtration: The crude nickel-cobalt powder was immersed in a sulfuric acid solution with a concentration of 2.5 mol / L for acid leaching treatment to obtain an acid leaching solution containing nickel and cobalt.

[0063] The acid leaching solution is purified by a chelating composite membrane to obtain a purified nickel-cobalt solution; wherein, the functional groups of the chelating composite membrane that retain nickel and cobalt ions include aminophosphonic acid groups, and the chelating composite membrane is a Tulsimer® CH-27 phosphonic acid composite membrane (from Kehaisi Technology Co., Ltd.).

[0064] (5) Post-processing: The purified nickel-cobalt solution was back-extracted using sulfuric acid solution to obtain a nickel-cobalt-containing back-extractant.

[0065] The back-extraction solution is evaporated and concentrated, and then a reduction reaction is carried out at 600°C for 2.5 h to obtain product-grade nickel-cobalt powder; wherein the reducing atmosphere is a nitrogen atmosphere containing hydrogen, and the volume fraction of hydrogen is 10%.

[0066] Example 2 This embodiment provides a method for recycling valuable metals from waste nickel-based superalloys, the recycling method comprising the following steps: (1) Pretreatment: The waste nickel-based superalloy was crushed to a particle size D50 of 1 mm, then immersed in a 1.5 mol / L sodium hydroxide solution for alkaline degreasing at 45°C for 60 min, followed by immersion in a 1 mol / L hydrochloric acid solution for acidic deoxidation at 30°C for 30 min. After the treatment, the waste was removed and vacuum dried to obtain the material to be treated.

[0067] (2) Extraction: The material to be treated and the molten Mg-M alloy were mixed at a mass ratio of 1:3, and then an extraction reaction was carried out at 700°C for 24 hours under a nitrogen atmosphere with stirring during the reaction. After the reaction, the mixture was filtered through a high-temperature resistant ceramic membrane to separate the nickel-cobalt eutectic and alloy residue. In the molten Mg-M alloy, M is Sn; the molar percentage of Mg in the molten Mg-M alloy is 45%; the pore size of the high-temperature resistant ceramic membrane is 5μm, and the material is alumina (alumina ceramic membrane from Jiangsu Jiuwu High-Tech Co., Ltd.).

[0068] (3) Vacuum distillation: The nickel-cobalt eutectic was subjected to primary distillation to recover Mg metal under a vacuum of 1 Pa and a temperature of 1100 °C, and then subjected to a vacuum of 1 × 10⁻⁶ Pa. -2 The M metal was recovered by two-stage distillation under the conditions of Pa and temperature of 1500℃ to obtain crude nickel-cobalt powder.

[0069] (4) Acid leaching and membrane filtration: The crude nickel-cobalt powder is immersed in a sulfuric acid solution with a concentration of 1 mol / L for acid leaching treatment to obtain an acid leaching solution containing nickel and cobalt.

[0070] The acid leaching solution is purified by a chelating composite membrane to obtain a purified nickel-cobalt solution; wherein, the functional groups of the chelating composite membrane that retain nickel and cobalt ions include aminophosphonic acid groups, and the chelating composite membrane is a Tulsimer® CH-27 phosphonic acid composite membrane (from Kehaisi Technology Co., Ltd.).

[0071] (5) Post-processing: The purified nickel-cobalt solution was back-extracted using sulfuric acid solution to obtain a nickel-cobalt-containing back-extractant.

[0072] The back-extraction solution is evaporated and concentrated, and then a reduction reaction is carried out at 400°C for 4 hours to obtain product-grade nickel-cobalt powder; wherein the reducing atmosphere is a nitrogen atmosphere containing hydrogen, and the volume fraction of hydrogen is 10%.

[0073] Example 3 This embodiment provides a method for recycling valuable metals from waste nickel-based superalloys, the recycling method comprising the following steps: (1) Pretreatment: The waste nickel-based superalloy was crushed to a particle size D50 of 3 mm, then immersed in a 2 mol / L sodium hydroxide solution for alkaline degreasing at 85°C for 10 min, and then immersed in a 3 mol / L hydrochloric acid solution for acidic deoxidation at 60°C for 10 min. After the treatment, the waste was removed and vacuum dried to obtain the material to be treated.

[0074] (2) Extraction: The material to be treated and the molten Mg-M alloy were mixed at a mass ratio of 1:10, and then an extraction reaction was carried out at 1000°C for 3 hours under a nitrogen atmosphere with stirring during the reaction. After the reaction, the mixture was filtered through a high-temperature resistant ceramic membrane to separate the nickel-cobalt eutectic and alloy residue. In the molten Mg-M alloy, M is Sn; the molar percentage of Mg in the molten Mg-M alloy is 75%; the pore size of the high-temperature resistant ceramic membrane is 5μm, and the material is alumina (alumina ceramic membrane from Jiangsu Jiuwu High-Tech Co., Ltd.).

[0075] (3) Vacuum distillation: The nickel-cobalt eutectic was subjected to primary distillation to recover Mg metal under a vacuum of 10 Pa and a temperature of 1300 °C, and then subjected to a vacuum of 1 × 10⁻⁶ Pa. -1 The M metal was recovered by two-stage distillation under the conditions of Pa and temperature of 1800℃ to obtain crude nickel-cobalt powder.

[0076] (4) Acid leaching and membrane filtration: The crude nickel-cobalt powder was immersed in a sulfuric acid solution with a concentration of 4 mol / L for acid leaching treatment to obtain an acid leaching solution containing nickel and cobalt.

[0077] The acid leaching solution is purified by a chelating composite membrane to obtain a purified nickel-cobalt solution; wherein, the functional groups of the chelating composite membrane that retain nickel and cobalt ions include aminophosphonic acid groups, and the chelating composite membrane is a Tulsimer® CH-27 phosphonic acid composite membrane (from Kehaisi Technology Co., Ltd.).

[0078] (5) Post-processing: The purified nickel-cobalt solution was back-extracted using sulfuric acid solution to obtain a nickel-cobalt-containing back-extractant.

[0079] The back-extraction solution is evaporated and concentrated, and then a reduction reaction is carried out at 800°C for 1 hour to obtain product-grade nickel-cobalt powder; wherein the reducing atmosphere is a nitrogen atmosphere containing hydrogen, and the volume fraction of hydrogen is 10%.

[0080] Example 4 The difference between this embodiment and Embodiment 1 is that in the molten Mg-M alloy, M is Bi.

[0081] The remaining preparation methods and parameters are consistent with those in Example 1.

[0082] Example 5 The difference between this embodiment and embodiment 1 is that the membrane filtration in step (2) is replaced by the traditional centrifugal separation method.

[0083] The remaining preparation methods and parameters are consistent with those in Example 1.

[0084] Example 6 The difference between this embodiment and Embodiment 1 is that the vacuum degree is the same during the first-stage distillation and the second-stage distillation, which is 5 Pa.

[0085] The remaining preparation methods and parameters are consistent with those in Example 1.

[0086] Example 7 The difference between this embodiment and Embodiment 1 is that the temperature is the same during both the first-stage and second-stage distillation processes, which is 1200℃.

[0087] The remaining preparation methods and parameters are consistent with those in Example 1.

[0088] Comparative Example 1 The difference between this comparative example and Example 1 is that no alkaline degreasing treatment is performed in step (1).

[0089] The remaining preparation methods and parameters are consistent with those in Example 1.

[0090] Comparative Example 2 The difference between this comparative example and Example 1 is that no acidic deoxidation treatment is performed in step (1).

[0091] The remaining preparation methods and parameters are consistent with those in Example 1.

[0092] Comparative Example 3 The difference between this comparative example and Example 1 is that a chelating composite membrane is not used to filter the acid leaching solution in step (4).

[0093] The remaining preparation methods and parameters are consistent with those in Example 1.

[0094] Performance testing The purity and recovery rate of the product-grade nickel-cobalt powder provided in the above examples and comparative examples were tested using inductively coupled plasma optical emission spectrometry (ICP-OES).

[0095] The test results are shown in Table 2.

[0096] Table 2 analyze: As shown in Table 2, this invention first subjectes the waste nickel-based superalloy to alkaline degreasing and acidic deoxidation treatments to remove surface interfering substances, thereby ensuring more thorough contact between the molten Mg-M alloy and nickel-cobalt and improving extraction efficiency. Secondly, a chelating composite membrane is introduced to purify the acid leaching solution, selectively retaining Ni... 2+ Co 2+ This process effectively removes any remaining metallic impurities, further improving the purity of the recovered nickel and cobalt. Finally, through back-extraction, evaporation concentration, and reduction, product-grade nickel and cobalt powder is obtained. This recovery method significantly improves the recovery efficiency and product purity of valuable metals, achieving efficient and high-purity recovery of nickel and cobalt resources from waste nickel-based superalloys. The process is short, simple to operate, and has good economic and environmental benefits.

[0097] A comparison of Examples 1 and 4 shows that if M is Bi, then due to the weak reducing power of Bi and the lower extraction capacity of the melt formed with Mg for Ni and Co compared to Zn, the efficiency of Ni and Co entering the melt from the alloy phase decreases. After the extraction reaction, the content of Ni and Co in the nickel-cobalt eutectic is low, resulting in a decrease in the recovery rate of the final product-grade nickel-cobalt powder and a reduction in product purity.

[0098] As can be seen from the comparison between Example 1 and Example 5, if membrane filtration is replaced by traditional centrifugal separation, the separation effect of centrifugal separation is relatively poor, making it difficult to completely remove alloy residues. This results in the residues being mixed into the nickel-cobalt eutectic, leading to a decrease in the purity of the final product-grade nickel-cobalt powder and a slight decrease in the recovery rate.

[0099] A comparison of Examples 1 and 6 shows that if the vacuum level is the same during the first and second distillation processes, it is difficult to achieve accurate separation, and the purity of the nickel-cobalt powder will eventually decrease.

[0100] As can be seen from the comparison between Example 1 and Example 7, if the temperature is the same during the first-stage distillation and the second-stage distillation, metal impurities are easily carried away and retained, making it difficult to obtain high-purity crude nickel-cobalt powder, resulting in the purity of the final product nickel-cobalt powder not meeting the product-grade requirements.

[0101] As can be seen from the comparison between Example 1 and Comparative Example 1, if alkaline degreasing treatment is not performed in step (1), the oil stains such as machine oil and cutting fluid attached to the surface of the waste nickel-based alloy will not be removed. On the one hand, it will contaminate the subsequent acid deoxidation solution and reduce the acid washing effect; on the other hand, during the extraction stage, the oil stains will decompose to generate carbides that cover the alloy surface, hindering the extraction reaction, resulting in a decrease in the recovery rate of nickel and cobalt, and the carbon impurity content in the product will exceed the standard.

[0102] As can be seen from the comparison between Example 1 and Comparative Example 2, if acidic deoxidation treatment is not performed in step (1), the dense oxide layer on the surface of the waste nickel-based alloy will not be removed. This oxide layer will form a physical barrier during the extraction process to prevent Ni and Co from dissolving and diffusing into the melt, resulting in a large amount of valuable metal remaining in the alloy residue, causing a waste of resources.

[0103] As can be seen from the comparison between Example 1 and Comparative Example 3, if the chelating composite membrane is not used to filter the acid leaching solution in step (4), the metal impurity ions in the acid leaching solution cannot be effectively removed. In the subsequent back-extraction and reduction process, they will co-deposit with nickel and cobalt, resulting in the impurity content in the product-grade nickel and cobalt powder being much higher than the product-grade standard. At the same time, the purity of nickel and cobalt is low and cannot meet the requirements of the product grade.

[0104] It should be noted that the present invention is illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for recycling valuable metals from scrap nickel-based superalloys, characterized in that, The recycling method includes the following steps: Waste nickel-based superalloys were subjected to alkaline degreasing and acidic deoxidation treatments in sequence to obtain the material to be treated. The material to be treated and molten Mg-M alloy are mixed and subjected to an extraction reaction. After the reaction, a nickel-cobalt eutectic and an alloy residue are separated. In the molten Mg-M alloy, M is an auxiliary metal. The nickel-cobalt eutectic is subjected to vacuum distillation, and the separated crude nickel-cobalt powder is then acid-leached to obtain an acid leaching solution; the acid leaching solution is purified by a chelating composite membrane to obtain a purified nickel-cobalt solution. The purified nickel-cobalt solution was back-extracted, and the resulting back-extract was concentrated by evaporation and reduced to obtain product-grade nickel-cobalt powder.

2. The method for recycling valuable metals from waste nickel-based superalloys according to claim 1, characterized in that, The particle size D50 of the waste nickel-based superalloy is 0.1-5 mm.

3. The method for recycling valuable metals from waste nickel-based superalloys according to claim 1 or 2, characterized in that, In the alkaline degreasing process, the alkaline solution used includes any one or a combination of at least two of sodium hydroxide solution, sodium carbonate solution, or sodium phosphate solution. And / or, the alkaline degreasing treatment is performed at a temperature of 45-85°C for a time of 10-60 minutes; And / or, during the acidic deoxidation treatment, the acid solution used includes any one or a combination of at least two of hydrochloric acid solution, sulfuric acid solution, or nitric acid solution; And / or, the acidic deoxidation layer treatment is performed at a temperature of 30-60°C for a time of 10-30 minutes.

4. The method for recycling valuable metals from scrap nickel-based superalloys according to any one of claims 1-3, characterized in that, The auxiliary metal includes any one or a combination of at least two of Zn, Sn, or Pb. And / or, in the molten Mg-M alloy, the molar percentage content of Mg is 45-75%; And / or, the mass ratio of the material to be processed to the molten Mg-M alloy is 1:(3-10).

5. The method for recycling valuable metals from scrap nickel-based superalloys according to any one of claims 1-4, characterized in that, The extraction reaction is carried out at a temperature of 700-1000℃; And / or, the extraction reaction time is 3-24 h; And / or, the atmosphere of the extraction reaction is an inert atmosphere.

6. The method for recycling valuable metals from scrap nickel-based superalloys according to any one of claims 1-5, characterized in that, The separation method is membrane filtration; The membrane used in the membrane filtration process is a high-temperature resistant ceramic membrane.

7. The method for recycling valuable metals from scrap nickel-based superalloys according to any one of claims 1-6, characterized in that, The vacuum distillation includes sequential primary distillation and secondary distillation; The temperature of the first-stage distillation is 1100-1300℃, and the vacuum degree is 1-10Pa; The secondary distillation temperature is 1500-1800℃, and the vacuum degree is 1×10⁻⁶. -2 -1×10 -1 Pa.

8. The method for recycling valuable metals from scrap nickel-based superalloys according to any one of claims 1-7, characterized in that, During the acid leaching process, the acid solution used includes any one or a combination of at least two of sulfuric acid solution, hydrochloric acid solution, or nitric acid solution; And / or, in the chelating composite membrane, the functional groups that retain nickel and cobalt ions include aminophosphonic acid groups or imine diacetic acid groups.

9. The method for recycling valuable metals from scrap nickel-based superalloys according to any one of claims 1-8, characterized in that, During the back-extraction process, the back-extraction reagents used include any one or a combination of at least two of sulfuric acid solution, hydrochloric acid solution, or ammonium acetate solution. And / or, the reduction reaction is carried out at a temperature of 400-800℃ for a time of 1-4 hours.

10. The method for recycling valuable metals from scrap nickel-based superalloys according to any one of claims 1-9, characterized in that, The recycling method includes the following steps: (1) Pretreatment: The waste nickel-based superalloy is crushed to a particle size D50 of 0.1-5 mm, then immersed in an alkaline solution with a concentration of 0.5-2 mol / L for alkaline degreasing at 45-85℃ for 10-60 min, and then immersed in an acidic solution with a concentration of 0.5-3 mol / L for acidic deoxidation at 30-60℃ for 10-30 min. After the treatment, the waste is removed and vacuum dried to obtain the material to be treated. (2) Extraction: The material to be treated and the molten Mg-M alloy are mixed at a mass ratio of 1:(3-10), and then an extraction reaction is carried out at 700-1000℃ under an inert atmosphere for 3-24 hours, with stirring during the reaction. After the reaction, the mixture is filtered through a high-temperature resistant ceramic membrane to separate the nickel-cobalt eutectic and alloy residue. In the molten Mg-M alloy, M is an auxiliary metal, which includes any one or a combination of at least two of Zn, Sn, or Pb. The molar percentage of Mg in the molten Mg-M alloy is 45-75%. The pore size of the high-temperature resistant ceramic membrane is 0.1-10 μm. (3) Vacuum distillation: The nickel-cobalt eutectic was subjected to primary distillation to recover Mg metal under vacuum conditions of 1-10 Pa and temperature of 1100-1300 °C, and then subjected to a vacuum of 1×10 Pa. -2 -1×10 -1 Under conditions of Pa and temperature of 1500-1800℃, two-stage distillation was carried out to recover M metal, yielding crude nickel-cobalt powder; (4) Acid leaching and membrane filtration: The crude nickel-cobalt powder is immersed in an acid solution with a concentration of 1-4 mol / L for acid leaching treatment to obtain an acid leaching solution containing nickel and cobalt. The acid leaching solution is purified by using a chelating composite membrane to obtain a purified nickel-cobalt solution; wherein, the functional groups in the chelating composite membrane that retain nickel and cobalt ions include aminophosphonic acid groups or imine diacetic acid groups. (5) Post-processing: The purified nickel-cobalt solution is back-extracted using a back-extraction reagent to obtain a nickel-cobalt-containing back-extraction solution; wherein the back-extraction reagent includes any one or a combination of at least two of sulfuric acid solution, hydrochloric acid solution, or ammonium acetate solution; The back-extraction solution is evaporated and concentrated, and then a reduction reaction is carried out in a reducing atmosphere at 400-800℃ for 1-4 hours to obtain product-grade nickel-cobalt powder; wherein the reducing gas in the reducing atmosphere includes a hydrogen atmosphere.

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