Method for recovering tungsten-containing waste material

Abstract

The application provides a tungsten-containing waste material recycling method, which comprises the following steps: pre-sintering treatment is performed on the tungsten-containing waste material to obtain a tungsten-based pre-sintered ingot; electron beam melting and water quenching are sequentially performed on the tungsten-based pre-sintered ingot to obtain water-quenched tungsten-containing particles; oxidation treatment is performed on the water-quenched tungsten-containing particles to obtain crude tungsten-based oxide particles; alkali leaching reaction and acid leaching precipitation are sequentially performed on the crude tungsten-based oxide particles to obtain refined tungsten-based oxide particles; reduction treatment is performed on the refined tungsten-based oxide particles to obtain metal tungsten powder and / or tungsten alloy powder. The recycling method provided by the application has the advantages of simple process flow, controllable operation, effective regulation and control of tungsten recovery purity, significantly improved tungsten recovery rate, excellent economic benefits and industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of metal metallurgy technology, and specifically relates to a method for recycling tungsten-containing waste materials. Background Technology

[0002] Tungsten alloys possess properties such as high melting point, high density, excellent corrosion resistance, and high-temperature strength, making them widely used in aerospace, military equipment, electronics, and nuclear energy. However, tungsten is a non-renewable and scarce strategic resource with limited and unevenly distributed global reserves. With the continuous mining and consumption of tungsten resources, the grade of primary tungsten ore is declining, mining costs are rising, and the supply-demand imbalance is becoming increasingly prominent. Therefore, given the current shortage of tungsten resources, developing an economical, efficient, and environmentally friendly method for recycling tungsten-containing waste is of great significance for socio-economic and ecological benefits.

[0003] Currently, common methods for recycling tungsten-containing waste materials include chemical recycling, oxidation-reduction, and vacuum distillation. For example, patent CN119040666A discloses a method for recycling tungsten and tungsten alloys from tungsten-containing waste materials, including the following steps: plasma melting of clean tungsten-containing profiles in an atmospheric environment; water quenching of the molten liquid to obtain water-quenched tungsten-containing particles; primary crushing of the water-quenched tungsten-containing particles to obtain crushed tungsten-containing particles; oxidation treatment of the crushed tungsten-containing particles to obtain oxide particles; sequential air jet milling and sieving of the oxide particles to obtain sieved powder; and reduction treatment of the sieved powder to obtain tungsten powder and / or tungsten alloy powder. Patent CN106145114A provides a method for recycling tungsten carbide and metallic cobalt from waste tungsten-cobalt cemented carbide. The process flow is as follows: cleaning and drying waste tungsten-cobalt cemented carbide, vacuum extraction of cobalt in a graphite crucible, obtaining loose, porous tungsten carbide from the crucible, crushing and grinding the loose, porous tungsten carbide to obtain tungsten carbide powder, and then condensing and crystallizing it in a cobalt crystallizer to obtain metallic cobalt powder. Although the above-mentioned existing patents can achieve resource recovery of tungsten-containing waste to a certain extent, there are still problems such as uncontrollable tungsten recovery purity and low recovery rate.

[0004] Therefore, how to balance the controllability of tungsten recovery purity with the improvement of recovery rate is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for recycling tungsten-containing waste. The invention first pre-sintersects the tungsten-containing waste into tungsten-based pre-sintered ingots, effectively reducing melt splashing during subsequent electron beam melting and improving the stability and safety of the melting process. Subsequently, through the synergistic treatment of electron beam melting and water quenching, the high temperature and high energy density characteristics of the electron beam allow impurity elements to fully volatilize or segregate, while rapid cooling by water quenching inhibits impurity redistribution, significantly reducing impurity entrainment and improving material purity. Furthermore, the crude tungsten-based oxide particles obtained from oxidation are sequentially subjected to alkaline leaching and acid leaching precipitation. Alkaline leaching selectively dissolves acidic impurities in the tungsten oxide, and acid leaching removes metallic impurities. The synergistic effect of these two processes significantly improves the purity of the tungsten-based oxide, laying a high-purity raw material foundation for subsequent reduction processes. In summary, the recycling method provided by the present invention has a simple process flow, is controllable, can effectively regulate the purity of tungsten recovery, and significantly improves the tungsten recovery rate, demonstrating excellent economic benefits and promising prospects for industrial application.

[0006] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for recycling tungsten-containing waste, the method comprising the following steps: Tungsten-containing waste materials are pre-sintered to obtain tungsten-based pre-sintered ingots.

[0007] The tungsten-based pre-sintered ingot was subjected to electron beam melting and water quenching in sequence to obtain water-quenched tungsten-containing particles.

[0008] The water-quenched tungsten-containing particles are subjected to oxidation treatment to obtain crude tungsten-based oxide particles.

[0009] The crude tungsten-based oxide particles were subjected to alkali leaching and acid leaching precipitation in sequence to obtain refined tungsten-based oxide particles.

[0010] The refined tungsten-based oxide particles are subjected to reduction treatment to obtain metallic tungsten powder and / or tungsten alloy powder.

[0011] This invention first pre-sintersects tungsten-containing waste materials into tungsten-based pre-sintered ingots, effectively reducing melt splashing during subsequent electron beam melting and improving the stability and safety of the melting process. Subsequently, through the synergistic treatment of electron beam melting and water quenching, the high temperature and high energy density characteristics of the electron beam allow impurity elements to fully volatilize or segregate, while rapid cooling by water quenching inhibits impurity redistribution, significantly reducing impurity entrainment and improving material purity. Furthermore, the crude tungsten-based oxide particles obtained from oxidation are subjected to alkali leaching and acid leaching precipitation sequentially. Alkali leaching selectively dissolves acidic impurities in the tungsten oxide, and acid leaching removes metallic impurities. The synergistic effect of these two processes significantly improves the purity of the tungsten-based oxide, laying a high-purity raw material foundation for subsequent reduction processes. In summary, the recycling method provided by this invention has a simple process flow, is controllable, and can effectively regulate the purity of tungsten recovery, while significantly improving the tungsten recovery rate, demonstrating excellent economic benefits and promising prospects for industrial application.

[0012] Preferably, the tungsten-containing waste material is further crushed before pre-sintering treatment to a particle size of 5-10 mm, such as 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm.

[0013] Preferably, the pre-sintering method is vacuum hot pressing sintering.

[0014] In this invention, vacuum hot pressing sintering is used for pre-sintering, which can effectively avoid oxidation of tungsten-containing waste materials during the heating process. At the same time, the pressure significantly improves the density and mechanical strength of the pre-sintered ingot, thereby further reducing melt splashing and gas release during the subsequent electron beam melting process and improving the stability and safety of the melting process.

[0015] Preferably, the vacuum degree of the vacuum hot pressing sintering is ≤1×10⁻⁶. -3 Pa, for example, could be 1×10 -3 Pa, 0.8×10 -3 Pa, 0.6×10 -3 Pa, 0.5×10 -3 Pa, 0.2×10 -3 Pa or 0.1×10 -3 Pa, etc.

[0016] Preferably, the temperature of the vacuum hot pressing sintering is 1200-1400℃, for example, it can be 1200℃, 1250℃, 1300℃, 1350℃ or 1400℃.

[0017] Preferably, during the vacuum hot pressing sintering process, the pressure applied to the tungsten-containing waste material is 40-60 MPa, for example, it can be 40 MPa, 45 MPa, 50 MPa, 55 MPa or 60 MPa, etc.

[0018] In the process of vacuum hot pressing sintering, the present invention applies appropriate pressure to tungsten-containing waste material simultaneously, which can promote close contact and interfacial diffusion between tungsten particles, eliminate internal pores, and obtain tungsten-based pre-sintered ingots with high density, thereby reducing melt splashing and improving melting effect during electron beam melting.

[0019] Preferably, the holding time for vacuum hot pressing sintering is 80-120 min, for example, it can be 80 min, 90 min, 100 min, 110 min or 120 min.

[0020] Preferably, the electron beam melting step includes: The tungsten-based pre-sintered ingot was placed in the crucible of an electron beam horizontal furnace and a vacuum was drawn.

[0021] The tungsten-based pre-sintered ingot is melted using a circular scanning beam spot, and then the process is switched to a square scanning beam spot for refining.

[0022] This invention employs an electron beam melting process of "circular scanning beam spot melting + square scanning beam spot refining", which significantly improves refining efficiency and impurity removal rate, while reducing energy consumption and melting loss.

[0023] Preferably, the particle size of the water-quenched tungsten particles is 2-3 mm, for example, it can be 2.0 mm, 2.2 mm, 2.5 mm, 2.8 mm or 3.0 mm.

[0024] Preferably, the power during the refining process is 25-35kW, for example, it can be 25kW, 28kW, 30kW, 32kW or 35kW, etc.

[0025] Preferably, the refining process takes 20-30 minutes, for example, 20 minutes, 22 minutes, 25 minutes, 28 minutes, or 30 minutes.

[0026] Preferably, before the tungsten-containing particles are oxidized after water quenching, they are first ground to make the particle size 20-200μm, for example, 20μm, 50μm, 100μm, 150μm or 200μm.

[0027] Preferably, the oxidation treatment temperature is 700-900℃, for example, 700℃, 750℃, 800℃, 850℃ or 900℃, and the holding time is 1-3h, for example, 1h, 1.5h, 2h, 2.5h or 3h.

[0028] Preferably, the atmosphere for the oxidation treatment is an oxygen-containing atmosphere. Examples include air, oxygen, or ozone.

[0029] Preferably, the crude tungsten-based oxide particles are subjected to air jet milling before being subjected to alkaline leaching.

[0030] Preferably, during the air jet milling process, the pressure is 0.6-0.8 MPa, for example, 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa or 0.8 MPa, and the rotation speed is 3000-5000 rpm, for example, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm or 5000 rpm.

[0031] Preferably, the atmosphere used during the air jet milling process is an inert atmosphere. Examples include nitrogen or argon.

[0032] This invention employs an inert atmosphere for air jet milling, which can thoroughly refine the coarse tungsten-based oxide particles, increasing their specific surface area and reactivity. At the same time, the inert atmosphere can prevent oxidation. The oxide particles treated by air jet milling lay a good foundation for subsequent alkaline and acid leaching processes, further improving the tungsten recovery rate and product purity.

[0033] Preferably, during the alkaline leaching reaction, the liquid-to-solid ratio of the alkaline solution to the crude tungsten-based oxide particles is (3-5):1, for example, it can be 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, etc.

[0034] For example, the alkaline solution may be a sodium hydroxide solution, potassium hydroxide solution, ammonia water, or sodium carbonate solution, etc.

[0035] Preferably, the temperature of the alkaline leaching reaction is 80-100℃, for example, 80℃, 85℃, 90℃, 95℃ or 100℃, and the time is 1-2h, for example, 1h, 1.2h, 1.5h, 1.8h or 2h.

[0036] Preferably, during the acid leaching and precipitation process, the pH of the reaction system is 1-2, for example, it can be 1.0, 1.2, 1.5, 1.8, or 2.0. For example, the acid solution used in the acid leaching and precipitation process can be hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid.

[0037] Preferably, the atmosphere for the reduction treatment is a reducing atmosphere. For example, it could be hydrogen.

[0038] Preferably, the reduction treatment temperature is 600-800℃, for example, 600℃, 650℃, 700℃, 750℃ or 800℃, and the time is 1-3h, for example, 1h, 1.5h, 2h, 2.5h or 3h.

[0039] Preferably, the recycling method includes the following steps: (1) Provide tungsten-containing waste materials.

[0040] The tungsten-containing waste material is immersed in an alkaline solution (such as sodium hydroxide solution) to remove oil and oxide layer, then washed with water until pH neutral, and then ultrasonically cleaned for 5-10 minutes (e.g., 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes). Subsequently, it is dried and crushed to obtain pretreated tungsten-containing waste material with a particle size of 5-10 mm.

[0041] (2) Place the pretreated tungsten-containing waste material in a vacuum hot press furnace and evacuate it to a vacuum level of ≤1×10⁻⁶. -3 Pa, heat to 1200-1400℃, apply a pressure of 40-60MPa to the pretreated tungsten-containing waste material, hold for 80-120min, cool, and remove the tungsten-based pre-sintered ingot.

[0042] (3) Place the tungsten-based pre-sintered ingot into the crucible of the electron beam horizontal furnace, and evacuate the melting chamber to ≤1×10⁻⁶. -2 Pa (for example, it could be 1 × 10) -2 Pa, 0.8×10 -2 Pa, 0.6×10 -2 Pa, 0.5×10 -2 Pa, 0.2×10 -2 Pa or 0.1×10 -2 Pa), the gun body is evacuated to ≤1×10 -3 Pa (for example, it could be 1 × 10) -3 Pa, 0.8×10 -3 Pa, 0.6×10 -3 Pa, 0.5×10 -3 Pa, 0.2×10 -3 Pa or 0.1×10 -3 Pa), preheat the electron gun for 20-40 minutes (e.g., 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes, etc.).

[0043] The tungsten-based pre-sintered ingot is melted using a circular scanning beam spot. After complete melting, the process is switched to a square scanning beam spot and refined for 20-30 minutes at a power of 25-35kW to obtain a refined eutectic.

[0044] The temperature of the water quenching container is controlled at 20-30℃ (e.g., 20℃, 22℃, 25℃, 28℃ or 30℃, etc.), and the refined eutectic is subjected to water quenching treatment to obtain water-quenched tungsten-containing particles with a particle size of 2-3mm.

[0045] (4) Under the conditions of ball-to-material ratio of (8-10):1 (e.g., 8:1, 8.5:1, 9:1, 9.5:1 or 10:1, etc.) and rotation speed of 200-300 rpm (e.g., 200 rpm, 225 rpm, 250 rpm, 275 rpm or 300 rpm, etc.), the water-quenched tungsten-containing particles are ball-milled to a particle size of 20-200 μm, and then placed in a high-temperature oxidation furnace and heated to 700-900℃ at a heating rate of 5-15℃ / min (e.g., 5℃ / min, 7.5℃ / min, 10℃ / min, 12.5℃ / min or 15℃ / min, etc.), and held for 1-3 hours to obtain tungsten-based oxide particles mainly composed of WO3.

[0046] The tungsten-based oxide particles are subjected to air jet milling at a pressure of 0.6-0.8 MPa (e.g., nitrogen) at a speed of 3000-5000 rpm. After sieving, coarse tungsten-based oxide powder with a particle size of 10-50 μm (e.g., 10 μm, 20 μm, 30 μm, 40 μm or 50 μm) is obtained.

[0047] The crude tungsten-based oxide powder and an alkaline solution with a concentration of 20-30 wt% (e.g., 20 wt%, 22 wt%, 25 wt%, 28 wt%, or 30 wt%) are mixed at a liquid-solid ratio of (3-5):1, and then stirred and reacted at 80-100℃ for 1-2 hours. After filtration, a filtrate containing tungsten salt is obtained.

[0048] The filtrate and acid solution are mixed, and the pH of the solution system is adjusted to 1-2 to precipitate the precipitate. The precipitate is washed with water and dried to obtain refined tungsten-based oxide particles.

[0049] (5) The refined tungsten-based oxide particles are placed in a high-temperature reduction furnace with a reducing atmosphere and heated to 600-800℃ at a heating rate of 5-15℃ / min (e.g., 5℃ / min, 7.5℃ / min, 10℃ / min, 12.5℃ / min or 15℃ / min, etc.) for 1-3 hours. After the process is completed, the particles are cooled to obtain metallic tungsten powder.

[0050] It should be noted that the alkaline solution in step (1) can be recycled after being left to stand to remove impurities after soaking. The waste liquid after the precipitate is precipitated in step (4) can be reused after being neutralized to 6-8.

[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 pre-sintersects tungsten-containing waste materials into tungsten-based pre-sintered ingots, effectively reducing melt splashing during subsequent electron beam melting and improving the stability and safety of the melting process. Subsequently, through the synergistic treatment of electron beam melting and water quenching, the high temperature and high energy density characteristics of the electron beam allow impurity elements to fully volatilize or segregate, while rapid cooling by water quenching inhibits impurity redistribution, significantly reducing impurity entrainment and improving material purity. Furthermore, the crude tungsten-based oxide particles obtained from oxidation are subjected to alkali leaching and acid leaching precipitation sequentially. Alkali leaching selectively dissolves acidic impurities in the tungsten oxide, and acid leaching removes metallic impurities. The synergistic effect of these two processes significantly improves the purity of the tungsten-based oxide, laying a high-purity raw material foundation for subsequent reduction processes. In summary, the recycling method provided by this invention has a simple process flow, is controllable, and can effectively regulate the purity of tungsten recovery, while significantly improving the tungsten recovery rate, demonstrating excellent economic benefits and promising prospects for industrial application. 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] Example 1 This embodiment provides a method for recycling tungsten-containing waste, the method comprising the following steps: (1) Provide tungsten wire waste; wherein the tungsten wire waste has a tungsten content of 85.7% by mass.

[0059] The tungsten wire waste was immersed in a 5 wt% sodium hydroxide solution to remove oil and oxide layers, then washed with water until the pH was neutral, and then ultrasonically cleaned for 8 minutes. Subsequently, it was dried at 200°C for 3 minutes to obtain clean tungsten wire. The clean tungsten wire was crushed to obtain pretreated tungsten-containing waste with a particle size of 5-10 mm. The sodium hydroxide solution was left to stand after immersion to remove impurities for recycling.

[0060] (2) The pretreated tungsten-containing waste is placed in a vacuum hot press furnace and evacuated to a vacuum level of <1×10⁻⁶. -3 Pa, heat to 1300℃, apply 50MPa pressure to the pretreated tungsten-containing waste material, hold for 100min, cool to 400℃ to break the air, and take out the tungsten-based pre-sintered ingot.

[0061] (3) Place the tungsten-based pre-sintered ingot into the crucible of the electron beam horizontal furnace, clean the furnace interior, and close the furnace door; evacuate the melting chamber to <1×10⁻⁶. -2 Pa, the gun body is evacuated to <1×10 -3 Pa, electron gun preheating for 30 minutes.

[0062] The tungsten-based pre-sintered ingot was melted using a circular scanning beam spot. After complete melting, the process was switched to a square scanning beam spot and refined for 25 minutes at a power of 30kW to obtain a refined eutectic.

[0063] The temperature of the water quenching tank is controlled at 25°C, and the refined eutectic is subjected to water quenching treatment to obtain water-quenched tungsten-containing particles with a particle size of 2-3 mm.

[0064] (4) Under the conditions of ball-to-material ratio of 9:1 and rotation speed of 250 rpm, the water-quenched tungsten-containing particles are ball-milled to a particle size of 20-200 μm, and then placed in a high-temperature oxidation furnace, heated to 800℃ at a heating rate of 10℃ / min, and held for 2 hours to obtain tungsten-based oxide particles mainly composed of WO3.

[0065] The tungsten-based oxide particles were subjected to air jet milling at 4000 rpm under a nitrogen atmosphere with a pressure of 0.7 MPa, and then sieved through a 200-mesh sieve to obtain coarse tungsten-based oxide powder with a particle size of 10-50 μm.

[0066] The crude tungsten-based oxide powder and a 25 wt% sodium hydroxide solution were mixed at a liquid-solid ratio of 4:1, and then stirred at 90°C for 1.5 h. After filtration, a filtrate containing tungsten salt was obtained.

[0067] The filtrate was mixed with sulfuric acid, and the pH of the solution system was adjusted to 1.5 to precipitate tungstic acid. After washing with pure water four times, the precipitate was dried at 120°C for 2 hours to obtain refined tungsten oxide powder. The waste liquid obtained after the precipitate of tungstic acid was neutralized to pH 7 and then reused.

[0068] (5) The refined tungsten oxide powder is placed in a high-temperature reduction furnace under hydrogen atmosphere and heated to 700°C at a heating rate of 10°C / min for 2 hours for reduction treatment. After the reduction treatment is completed, it is cooled to room temperature of 25°C under nitrogen protection to obtain metallic tungsten powder.

[0069] Example 2 This embodiment provides a method for recycling tungsten-containing waste, the method comprising the following steps: (1) Provide tungsten wire waste; wherein the tungsten wire waste has a tungsten content of 85.7% by mass.

[0070] The tungsten wire waste was immersed in a 5 wt% sodium hydroxide solution to remove oil and oxide layers, then washed with water until the pH was neutral, and ultrasonically cleaned for 5 minutes. Subsequently, it was dried at 200°C for 3 minutes to obtain clean tungsten wire. The clean tungsten wire was crushed to obtain pretreated tungsten-containing waste with a particle size of 5-10 mm. The sodium hydroxide solution was left to stand after immersion to remove impurities for recycling.

[0071] (2) The pretreated tungsten-containing waste is placed in a vacuum hot press furnace and evacuated to a vacuum level of <1×10⁻⁶. -3 Pa, heat to 1200℃, apply a pressure of 60MPa to the pretreated tungsten-containing waste material, hold for 120min, cool to 400℃ to break the air, and take out the tungsten-based pre-sintered ingot.

[0072] (3) Place the tungsten-based pre-sintered ingot into the crucible of the electron beam horizontal furnace, clean the furnace interior, and close the furnace door; evacuate the melting chamber to <1×10⁻⁶. -2 Pa, the gun body is evacuated to <1×10 -3 Pa, electron gun preheating for 20 minutes.

[0073] The tungsten-based pre-sintered ingot was melted using a circular scanning beam spot. After complete melting, the process was switched to a square scanning beam spot and refined for 30 minutes at a power of 25kW to obtain a refined eutectic.

[0074] The temperature of the water quenching tank is controlled at 20℃, and the refined eutectic is subjected to water quenching treatment to obtain water-quenched tungsten-containing particles with a particle size of 2-3mm.

[0075] (4) Under the conditions of ball-to-material ratio of 8:1 and rotation speed of 200 rpm, the water-quenched tungsten-containing particles are ball-milled to a particle size of 20-200 μm, and then placed in a high-temperature oxidation furnace, heated to 700℃ at a heating rate of 5℃ / min, and kept at the temperature for 3h to obtain tungsten-based oxide particles mainly composed of WO3.

[0076] The tungsten-based oxide particles were subjected to air jet milling at 3000 rpm under a nitrogen atmosphere with a pressure of 0.6 MPa, and then sieved through a 200-mesh sieve to obtain coarse tungsten-based oxide powder with a particle size of 10-50 μm.

[0077] The crude tungsten-based oxide powder and a 25 wt% sodium hydroxide solution were mixed at a liquid-solid ratio of 3:1, and then stirred at 80°C for 2 hours. After filtration, a filtrate containing tungsten salt was obtained.

[0078] The filtrate was mixed with sulfuric acid, and the pH of the solution system was adjusted to 1 to precipitate tungstic acid. After washing with pure water four times, the precipitate was dried at 120°C for 2 hours to obtain refined tungsten oxide powder. The waste liquid obtained after the precipitate of tungstic acid in the solution system was neutralized to pH 7 and then reused.

[0079] (5) The refined tungsten oxide powder is placed in a high-temperature reduction furnace under hydrogen atmosphere and heated to 600°C at a heating rate of 5°C / min for 3 hours for reduction treatment. After the reduction treatment is completed, it is cooled to room temperature of 25°C under nitrogen protection to obtain metallic tungsten powder.

[0080] Example 3 This embodiment provides a method for recycling tungsten-containing waste, the method comprising the following steps: (1) Provide tungsten wire waste; wherein the tungsten wire waste has a tungsten content of 85.7% by mass.

[0081] The tungsten wire waste was immersed in a 5 wt% sodium hydroxide solution to remove oil and oxide layers, then washed with water until the pH was neutral, and then ultrasonically cleaned for 10 minutes. Subsequently, it was dried at 200°C for 3 minutes to obtain clean tungsten wire. The clean tungsten wire was crushed to obtain pretreated tungsten-containing waste with a particle size of 5-10 mm. The sodium hydroxide solution was left to stand after immersion to remove impurities for recycling.

[0082] (2) The pretreated tungsten-containing waste is placed in a vacuum hot press furnace and evacuated to a vacuum level of <1×10⁻⁶. -3 Pa, heat to 1400℃, apply a pressure of 40MPa to the pretreated tungsten-containing waste material, hold for 80 minutes, cool to 400℃ to break the air, and take out the tungsten-based pre-sintered ingot.

[0083] (3) Place the tungsten-based pre-sintered ingot into the crucible of the electron beam horizontal furnace, clean the furnace interior, and close the furnace door; evacuate the melting chamber to <1×10⁻⁶. -2 Pa, the gun body is evacuated to <1×10 -3 Pa, electron gun preheating for 40 minutes.

[0084] The tungsten-based pre-sintered ingot was melted using a circular scanning beam spot. After complete melting, the process was switched to a square scanning beam spot and refined for 20 minutes at a power of 35kW to obtain a refined eutectic.

[0085] The temperature of the water quenching tank is controlled at 30℃, and the refined eutectic is subjected to water quenching treatment to obtain water-quenched tungsten-containing particles with a particle size of 2-3mm.

[0086] (4) Under the conditions of ball-to-material ratio of 10:1 and rotation speed of 300 rpm, the water-quenched tungsten-containing particles are ball-milled to a particle size of 20-200 μm, and then placed in a high-temperature oxidation furnace, heated to 900℃ at a heating rate of 15℃ / min, and held for 1h to obtain tungsten-based oxide particles mainly composed of WO3.

[0087] The tungsten-based oxide particles were subjected to air jet milling at 5000 rpm under a nitrogen atmosphere with a pressure of 0.8 MPa, and then sieved through a 200-mesh sieve to obtain coarse tungsten-based oxide powder with a particle size of 10-50 μm.

[0088] The crude tungsten-based oxide powder and a 25 wt% sodium hydroxide solution were mixed at a liquid-solid ratio of 5:1, and then stirred at 100°C for 1 hour. After filtration, a filtrate containing tungsten salt was obtained.

[0089] The filtrate was mixed with sulfuric acid, and the pH of the solution system was adjusted to 2 to precipitate tungstic acid. After washing with pure water four times, the precipitate was dried at 120°C for 2 hours to obtain refined tungsten oxide powder. The waste liquid obtained after the precipitate of tungstic acid in the solution system was neutralized to pH 7 and then reused.

[0090] (5) The refined tungsten oxide powder is placed in a high-temperature reduction furnace under hydrogen atmosphere and heated to 800°C at a heating rate of 15°C / min for 1 hour for reduction treatment. After the reduction treatment is completed, it is cooled to room temperature of 25°C under nitrogen protection to obtain metallic tungsten powder.

[0091] Example 4 The difference between this embodiment and embodiment 1 is that in step (2), the vacuum hot press furnace is replaced by a tube furnace, and the atmosphere is argon atmosphere with atmospheric pressure.

[0092] The remaining recovery methods and parameters are consistent with those in Example 1.

[0093] Example 5 The difference between this embodiment and embodiment 1 is that, in step (2), no pressure is applied to the pretreated tungsten-containing waste material.

[0094] The remaining recovery methods and parameters are consistent with those in Example 1.

[0095] Example 6 The difference between this embodiment and embodiment 1 is that in step (3), after complete melting, the square scanning beam spot is not switched, that is, only the circular scanning beam spot is used throughout the process.

[0096] The remaining recovery methods and parameters are consistent with those in Example 1.

[0097] Example 7 The difference between this embodiment and embodiment 1 is that in step (3), instead of using circular scanning beams to melt tungsten-based pre-sintered ingots, square scanning beams are used directly for refining.

[0098] The remaining recovery methods and parameters are consistent with those in Example 1.

[0099] Example 8 The difference between this embodiment and embodiment 1 is that air jet milling is not performed in step (4).

[0100] The remaining recovery methods and parameters are consistent with those in Example 1.

[0101] Comparative Example 1 The difference between this comparative example and Example 1 is that water quenching is not performed in step (3).

[0102] The remaining recovery methods and parameters are consistent with those in Example 1.

[0103] Comparative Example 2 The difference between this comparative example and Example 1 is that in step (4), no alkaline leaching is performed, that is, no sodium hydroxide solution is added.

[0104] The remaining recovery methods and parameters are consistent with those in Example 1.

[0105] Comparative Example 3 The difference between this comparative example and Example 1 is that in step (4), acid leaching is not performed, that is, sulfuric acid is not added.

[0106] The remaining recovery methods and parameters are consistent with those in Example 1.

[0107] Performance testing The purity of the tungsten powders prepared in the above examples and comparative examples was tested using inductively coupled plasma optical emission spectrometry (ICP-OES), and the tungsten recovery rate was calculated.

[0108] The results are shown in Table 1.

[0109] Table 1 analyze: As shown in Table 1, this invention first pre-sintersects tungsten-containing waste materials into tungsten-based pre-sintered ingots, which effectively reduces melt splashing during subsequent electron beam melting and improves the stability and safety of the melting process. Subsequently, through the synergistic treatment of electron beam melting and water quenching, the high temperature and high energy density characteristics of the electron beam allow impurity elements to fully volatilize or segregate, while rapid cooling by water quenching inhibits impurity redistribution, significantly reducing impurity entrainment and improving material purity. Furthermore, the crude tungsten-based oxide particles obtained from oxidation are subjected to alkali leaching and acid leaching precipitation sequentially. Alkali leaching selectively dissolves acidic impurities in the tungsten oxide, and acid leaching removes metallic impurities. The synergistic effect of these two processes significantly improves the purity of the tungsten-based oxide, laying a high-purity raw material foundation for subsequent reduction processes. In summary, the recycling method provided by this invention has a simple process flow, is controllable, and can effectively regulate the purity of tungsten recovery, while significantly improving the tungsten recovery rate, demonstrating excellent economic benefits and promising prospects for industrial application.

[0110] As can be seen from the comparison between Example 1 and Example 4, if the vacuum hot press furnace in step (2) is replaced by a tube furnace, and the atmosphere is argon atmosphere and the pressure is atmospheric pressure, it is impossible to effectively remove the gas and low melting point impurities adsorbed on the surface of the tungsten wire waste. Moreover, without external pressure, the density of the pre-sintered ingot decreases, which easily causes violent splashing during subsequent electron beam melting, reduces melting stability, reduces impurity removal efficiency, and leads to a decrease in the purity of the obtained tungsten metal powder and a decrease in recovery rate.

[0111] As can be seen from the comparison between Example 1 and Example 5, if no pressure is applied to the pretreated tungsten-containing waste material in step (2), the pre-sintered ingot will have low density and poor mechanical strength. During electron beam melting, the melt will splash and a large number of pores will be generated during the melting process, resulting in severe impurity segregation, which will reduce the purity of the final tungsten powder and decrease the recovery rate.

[0112] As can be seen from the comparison between Example 1 and Example 6, if only circular scanning beam spot is used in step (3) throughout the process, the temperature distribution of the molten pool of the electron beam will be uneven, the impurities will not volatilize sufficiently during refining, and the purity of the product will be reduced.

[0113] As can be seen from the comparison between Example 1 and Example 7, if in step (3) the circular scanning beam spot is not used to melt the tungsten-based pre-sintered ingot, but the square scanning beam spot is used directly for refining, the overall smelting efficiency will decrease, there will be more residual impurities after refining, and the purity of the final tungsten powder will decrease, and the recovery rate will decrease.

[0114] As can be seen from the comparison between Example 1 and Example 8, if air jet milling is not performed in step (4), the crude tungsten-based oxide particles will have a large particle size and uneven distribution, and a small specific surface area, which is not conducive to the subsequent alkaline leaching and acid leaching processes. In the end, the purity of the tungsten powder will decrease and the recovery rate will decrease.

[0115] As can be seen from the comparison between Example 1 and Comparative Example 1, if water quenching is not performed in step (3), the refined eutectic will be slowly cooled, the grains will be coarse and the impurities will be resegregated, the subsequent oxidation treatment will be uneven, and the purity of the tungsten powder will decrease and the recovery rate will decrease.

[0116] As can be seen from the comparison between Example 1 and Comparative Example 2, if alkaline leaching is not performed in step (4), the acidic impurities in the crude tungsten-based oxide powder cannot be effectively removed, the direct acid leaching effect is poor, and the purity of the final obtained tungsten metal powder is reduced.

[0117] As can be seen from the comparison between Example 1 and Comparative Example 3, if acid leaching is not performed in step (4), the metal impurities in the filtrate containing tungsten salt after alkali leaching cannot be precipitated and removed, resulting in high impurity content and low purity of the reduced tungsten powder.

[0118] 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 tungsten-containing waste, characterized in that, The recycling method includes the following steps: Tungsten-containing waste materials are pre-sintered to obtain tungsten-based pre-sintered ingots; The tungsten-based pre-sintered ingot was sequentially subjected to electron beam melting and water quenching to obtain water-quenched tungsten-containing particles; The water-quenched tungsten-containing particles are subjected to oxidation treatment to obtain crude tungsten-based oxide particles; The crude tungsten-based oxide particles were subjected to alkali leaching and acid leaching precipitation in sequence to obtain refined tungsten-based oxide particles. The refined tungsten-based oxide particles are subjected to reduction treatment to obtain metallic tungsten powder and / or tungsten alloy powder.

2. The recycling method according to claim 1, characterized in that, Before undergoing pre-sintering treatment, the tungsten-containing waste material is also crushed to a particle size of 5-10 mm.

3. The recycling method according to claim 1 or 2, characterized in that, The pre-sintering method is vacuum hot pressing sintering; And / or, the vacuum degree of the vacuum hot pressing sintering is ≤1×10 -3 Pa; And / or, the temperature of the vacuum hot pressing sintering is 1200-1400℃; And / or, during the vacuum hot pressing sintering process, the pressure applied to the tungsten-containing waste material is 40-60 MPa; And / or, the holding time for the vacuum hot pressing sintering is 80-120 min.

4. The recycling method according to any one of claims 1-3, characterized in that, The electron beam melting process includes: The tungsten-based pre-sintered ingot was placed in an electron beam horizontal furnace crucible and evacuated. The tungsten-based pre-sintered ingot is melted using a circular scanning beam spot, and then the process is switched to a square scanning beam spot for refining. And / or, the particle size of the water-quenched tungsten-containing particles is 2-3 mm.

5. The recycling method according to claim 4, characterized in that, During the refining process, the power consumption is 25-35kW; And / or, the refining process takes 20-30 minutes.

6. The recycling method according to any one of claims 1-5, characterized in that, Before the water-quenched tungsten-containing particles undergo oxidation treatment, they are first ground to achieve a particle size of 20-200 μm. And / or, the oxidation treatment is performed at a temperature of 700-900℃ for a holding time of 1-3 hours; And / or, the atmosphere for the oxidation treatment is an oxygen-containing atmosphere.

7. The recycling method according to any one of claims 1-6, characterized in that, Before the crude tungsten-based oxide particles undergo alkaline leaching, they are first subjected to air jet milling. And / or, during the air jet milling process, the pressure is 0.6-0.8 MPa and the rotation speed is 3000-5000 rpm; And / or, the atmosphere during the air jet milling process is an inert atmosphere.

8. The recycling method according to any one of claims 1-7, characterized in that, During the alkaline leaching reaction, the liquid-to-solid ratio of the alkaline solution to the crude tungsten-based oxide particles is (3-5):

1. And / or, the alkaline leaching reaction is carried out at a temperature of 80-100°C for 1-2 hours; And / or, during the acid leaching precipitation process, the pH of the reaction system is 1-2.

9. The recycling method according to any one of claims 1-7, characterized in that, The atmosphere used in the reduction treatment is a reducing atmosphere; And / or, the reduction treatment is performed at a temperature of 600-800℃ for a time of 1-3 hours.

10. The recycling method according to any one of claims 1-9, characterized in that, The recycling method includes the following steps: (1) Provide tungsten-containing waste materials; The tungsten-containing waste material is soaked in an alkaline solution to remove oil and oxide layer, then washed with water until pH is neutral, and then ultrasonically cleaned for 5-10 minutes. After drying and crushing, pre-treated tungsten-containing waste material with a particle size of 5-10 mm is obtained. (2) Place the pretreated tungsten-containing waste material in a vacuum hot press furnace and evacuate it to a vacuum level of ≤1×10⁻⁶. -3 Pa, heat to 1200-1400℃, apply a pressure of 40-60MPa to the pretreated tungsten-containing waste material, hold for 80-120min, cool, and take out the tungsten-based pre-sintered ingot; (3) Place the tungsten-based pre-sintered ingot into the crucible of the electron beam horizontal furnace, and evacuate the melting chamber to ≤1×10⁻⁶. -2 Pa, the gun body is evacuated to ≤1×10 Pa. -3 Pa, electron gun preheating for 20-40 minutes; The tungsten-based pre-sintered ingot is melted using a circular scanning beam spot. After complete melting, the process is switched to a square scanning beam spot and refined for 20-30 minutes at a power of 25-35kW to obtain a refined eutectic. The temperature of the water quenching container is controlled at 20-30℃, and the refined eutectic is subjected to water quenching treatment to obtain water-quenched tungsten-containing particles with a particle size of 2-3mm. (4) Under the conditions of ball-to-material ratio of (8-10):1 and rotation speed of 200-300 rpm, the water-quenched tungsten-containing particles are ball-milled to a particle size of 20-200 μm, and then placed in a high-temperature oxidation furnace and heated to 700-900℃ at a heating rate of 5-15℃ / min, and kept at the temperature for 1-3 hours to obtain tungsten-based oxide particles with WO3 as the main component. The tungsten-based oxide particles were subjected to air jet milling at a speed of 3000-5000 rpm under an inert atmosphere with a pressure of 0.6-0.8 MPa, and after sieving, coarse tungsten-based oxide powder with a particle size of 10-50 μm was obtained. The crude tungsten-based oxide powder and an alkaline solution with a concentration of 20-30 wt% are mixed at a liquid-solid ratio of (3-5):1, and then stirred and reacted at 80-100℃ for 1-2 hours. After filtration, a filtrate containing tungsten salt is obtained. The filtrate and acid solution are mixed, and the pH of the solution system is adjusted to 1-2 to precipitate the precipitate. The precipitate is washed with water and dried to obtain refined tungsten-based oxide particles. (5) The refined tungsten-based oxide particles are placed in a high-temperature reduction furnace with a reducing atmosphere and heated to 600-800℃ at a heating rate of 5-15℃ / min for 1-3 hours for reduction treatment. After the treatment, the particles are cooled to obtain metallic tungsten powder.

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