A method for recovering tungsten and rhenium from tungsten-rhenium alloy waste

Abstract

This invention discloses a method for recovering tungsten and rhenium from tungsten-rhenium alloy waste, belonging to the field of waste metal recycling technology. The method includes: leaching pretreated tungsten-rhenium alloy waste by heating and stirring with a mixed solution of dilute hydrochloric acid and hydrogen peroxide, converting tungsten and rhenium into tungstate ions and perrhenate ions respectively into the solution; then, rapid acidification by quantitatively adding concentrated hydrochloric acid, causing tungsten to precipitate as crystalline tungstic acid; filtering to obtain a crystalline tungstic acid filter cake and a rhenium-containing filtrate; adsorbing the rhenium-containing filtrate through an anion exchange resin to load perrhenate ions onto the resin; subsequently eluting with an ammonia solution to obtain an ammonium perrhenate solution; evaporating, concentrating, and crystallizing to obtain ammonium perrhenate crystals; simultaneously washing and drying the tungstic acid filter cake to obtain the tungstic acid product. This invention features a simple process flow, thorough tungsten-rhenium separation, high recovery rate, is green and economical, and can obtain high-purity tungsten and rhenium products.

Description

Technical Field

[0001] This invention relates to the field of waste metal recycling technology, and in particular to a method for recovering tungsten and rhenium from tungsten-rhenium alloy waste. Background Technology

[0002] In the field of rare and precious metal recycling, tungsten-rhenium alloys, with their excellent high-temperature performance, are widely used in key industries such as aerospace and electronics. The grade of valuable metals in their waste is far higher than that of primary mineral resources, making their resource recovery value significant. Through recycling, not only can resource utilization be improved, but the energy consumption and environmental burden caused by primary ore mining can also be reduced, providing qualified raw materials for the reprocessing of high-end materials and enhancing the economic efficiency and sustainability of rare and precious metal recycling.

[0003] Currently, there are many shortcomings in the processes for recovering tungsten and rhenium from tungsten-rhenium alloy waste: pyrometallurgy relies on high-temperature sublimation for separation, which is energy-intensive, requires stringent equipment, and results in low rhenium recovery rates and insufficient product purity, making it difficult to adapt to large-scale production; traditional wet processes use single-reagent leaching, which has slow dissolution rates and low reagent utilization, and easily generates colloidal tungstic acid during acidic tungsten precipitation, making filtration difficult and easily adsorbing and entraining rhenium, resulting in metal loss; when rhenium-containing filtrate is directly evaporated, concentrated, and crystallized, the system is highly corrosive, faces significant environmental pressure, and produces products with high impurity content, making subsequent purification processes complex and costly.

[0004] To address the issue of tungstate colloid formation in the aforementioned acidic wet leaching process, recent studies have attempted to employ a strongly alkaline hydrogen peroxide system for synergistic oxidative leaching. For example, Chinese patent CN121294853A discloses a method that utilizes alkaline conditions to prevent tungstate precipitation, and after adjusting the pH of the leachate, directly separates tungstate and perrhenate ions using an anion exchange resin. While this route can mitigate the colloidal problem of acidic tungsten precipitation to some extent, the strongly alkaline system (such as OH⁻) presents challenges. - The concentration (2.0-4.0 mol / L) is extremely corrosive to equipment, requiring reactors and pipelines made of alkali-resistant materials. Furthermore, it often necessitates the introduction of oxidizing gases and ultrasonic assistance to enhance mass transfer, leading to complex processes, increased energy consumption, and significantly higher equipment investment and maintenance costs. In addition, this route retains both tungsten and rhenium in anionic form in solution, relying on the selectivity of ion exchange resins for the two anions to achieve separation. In practice, the competitive adsorption of tungstate and perrhenate is difficult to completely avoid, limiting the tungsten-rhenium separation efficiency.

[0005] Therefore, it is evident that in existing technologies, the acidic route struggles to achieve high purity and high recovery rates due to the colloidal tungstic acid problem, while the alkaline route, although avoiding the colloidal issue, introduces new technical bottlenecks such as strong corrosion and insufficient separation selectivity. Neither route satisfies the comprehensive requirements of a simple process flow, mild equipment requirements, thorough tungsten-rhenium separation, and high recovery rates. There is an urgent need to develop a novel recovery process that overcomes the colloidal defects of the acidic route, avoids the strong corrosion problems of the alkaline route, is green and economical, and can produce high-purity tungsten and rhenium products. This is of great significance for promoting the efficient recycling of tungsten and rhenium secondary resources. Summary of the Invention

[0006] This invention aims to address numerous problems existing in current tungsten-rhenium alloy waste recycling technologies: pyrometallurgical recovery suffers from high energy consumption, demanding equipment requirements, low rhenium recovery rates, and poor product purity; traditional wet leaching is inefficient, consumes large amounts of reagents, and acidic tungsten precipitation easily forms colloidal tungstic acid, making filtration difficult and causing rhenium adsorption and entrainment, resulting in metal loss; direct evaporation, concentration, and crystallization of rhenium-containing filtrate is highly corrosive and polluting, producing products with high impurity content, and the purification process is complex and costly. In particular, while existing alkaline leaching routes can avoid tungstic acid colloidal formation, their strong corrosiveness and equipment complexity limit their industrial application, and the competitive adsorption of tungsten and rhenium anions leads to incomplete separation. Therefore, this invention provides a highly efficient, low-consumption, and environmentally friendly method for recycling tungsten-rhenium alloy waste, achieving efficient separation and high-purity recovery of tungsten and rhenium, overcoming the colloidal defects of acidic routes and the strong corrosion defects of alkaline routes, improving the overall recovery rate, simplifying the process, and reducing production costs.

[0007] To achieve the above objectives, the technical solution adopted in this invention is as follows: An acidic synergistic oxidation leaching system composed of dilute hydrochloric acid and hydrogen peroxide is used to leach tungsten-rhenium alloy waste under heating and stirring conditions, allowing tungsten and rhenium to be fully oxidized and dissolved. Rapid acidification is achieved by quantitatively adding concentrated hydrochloric acid, causing tungsten to precipitate as crystalline tungstic acid. This optimizes the morphology and filtration performance of the precipitate particles, avoiding the formation of colloidal tungstic acid and its adsorption and entrainment of rhenium, thus achieving preliminary and efficient separation of tungsten and rhenium. This step differs from the existing alkaline route. The method of retaining tungsten in solution in anionic form differs from the existing acidic route where colloidal tungstic acid precipitates due to slow acidification or natural cooling. By controlling the acidification kinetics, tungsten is converted into an easily filterable crystalline solid phase, thereby achieving high recovery rate and high purity simultaneously with the liquid-solid separation of rhenium. The rhenium-containing filtrate is dynamically adsorbed and eluted by a chlorine-type strong base styrene-based anion exchange resin to obtain ammonium perrhenate solution, which is then dried to obtain ammonium perrhenate. The tungstic acid filter cake is washed and dried to obtain tungstic acid product.

[0008] The technical solution of the present invention is as follows: This invention provides a method for recovering tungsten and rhenium from tungsten-rhenium alloy waste, comprising the following steps: Step 1: Pre-treat the tungsten-rhenium alloy waste to obtain pre-treated waste fragments; Step 2: Place the pretreated waste fragments in a mixed solution of dilute hydrochloric acid and hydrogen peroxide, and carry out a leaching reaction under heating and stirring conditions to oxidize the tungsten and rhenium in the waste into tungstate ions and perrhenate ions, respectively, to obtain a mixed leachate containing tungstate and perrhenate ions. Step 3: Add concentrated hydrochloric acid to the mixed leachate, controlling the amount of concentrated hydrochloric acid added to be 5-15 mL per 100 mL of mixed leachate, so that tungsten precipitates out in the form of crystalline tungstic acid. After solid-liquid separation, crystalline tungstic acid filter cake and rhenium-containing filtrate are obtained, thereby achieving the separation of tungsten and rhenium. Step 4: The rhenium-containing filtrate is dynamically adsorbed through an anion exchange resin to load perrhenate ions onto the resin. Step 5: Elute the rhenium-loaded resin with an ammonia solution and collect the eluent to obtain an ammonium perrhenate solution; Step 6: Wash and dry the tungstic acid filter cake to obtain the tungstic acid product; Step 7: The ammonium perrhenate solution is evaporated, concentrated, and crystallized to obtain ammonium perrhenate crystals.

[0009] Preferably, the pretreatment in step 1 includes: crushing the tungsten-rhenium alloy waste and passing it through a 10-20 mesh sieve, then ultrasonically cleaning it in anhydrous ethanol for 15-30 minutes, and finally drying it at 80-100℃ for 2-4 hours.

[0010] Preferably, the ultrasonic cleaning uses an ultrasonic frequency of 30-50kHz and an ultrasonic power of 200-300W.

[0011] As a further explanation of the present invention, the pretreatment can increase the contact area between the waste and the leaching system, while removing surface oil, cutting fluid residue and organic impurities, thereby improving the efficiency of subsequent leaching reactions and the purity of the solution.

[0012] Preferably, in step 2, the mixed solution is composed of dilute hydrochloric acid and hydrogen peroxide mixed in a volume ratio of (1-2):1.

[0013] Preferably, the concentration of the dilute hydrochloric acid is 0.5-1.5 mol / L, and the concentration of the hydrogen peroxide is 25-35 wt%.

[0014] Preferably, in step 2, the liquid-to-solid ratio of the mixed solution to the waste fragments is (3-7):1mL / g.

[0015] Preferably, in step 2, the leaching temperature is 80-95℃, the leaching time is 1-3h, and the stirring rate is 200-400r / min.

[0016] Preferably, in step 3, the concentration of the concentrated hydrochloric acid is 36-38 wt%.

[0017] Preferably, in step 4, the anion exchange resin is a chlorinated strong basic styrene-based anion exchange resin; and the flow rate of the rhenium-containing filtrate through the column is 1-3 BV / h.

[0018] In further explanation of the present invention, in step 4, the perrhenate anions in the rhenium-containing filtrate exchange with the chloride ions on the resin and are loaded onto the resin, thereby enabling the perrhenate ions to be loaded onto the resin.

[0019] Preferably, in step 5, before adsorption, the resin is washed with water, and the amount of water used for washing is 1-2 BV.

[0020] Preferably, in step 5, the concentration of the ammonia solution is 5-12 wt%; the elution flow rate is 0.5-2 BV / h; and the amount of ammonia solution used is 2-3 BV.

[0021] In further explanation of the present invention, in step 5, the resin is washed with water before adsorption in order to remove residual acid and soluble impurities entrained in the resin gaps. Subsequently, the resin loaded with rhenium is dynamically eluted with an ammonia solution. Perrhenate ions combine with ammonia to form ammonium perrhenate, which enters the liquid phase. The eluent is collected to obtain a high-purity ammonium perrhenate solution.

[0022] Preferably, in step 6, the tungstic acid filter cake is first washed with dilute hydrochloric acid 2-3 times, then rinsed with deionized water 2-3 times, and then dried at 120-150℃ for 4-6 hours.

[0023] Preferably, in step 7, the evaporation, concentration, and crystallization temperature is 120-150℃, and the evaporation, concentration, and crystallization time is 4-6 hours.

[0024] The present invention has the following beneficial effects: 1. This invention provides a method for recovering tungsten and rhenium from tungsten-rhenium alloy waste. The method employs an acidic synergistic oxidation leaching system (a mixed solution of dilute hydrochloric acid and hydrogen peroxide) to leach the tungsten-rhenium alloy waste, fully oxidizing and dissolving the tungsten and rhenium into soluble ions. This system has significantly lower equipment corrosivity than strongly alkaline systems, eliminating the need for equipment made of alkali-resistant materials and oxidizing gas assistance. The process is simple, environmentally friendly, and cost-effective. A quantitative amount of concentrated hydrochloric acid is rapidly added to the mixed leaching solution for acidification. By controlling the acidification conditions, tungstic acid precipitates in a crystalline rather than colloidal state, resulting in large crystal particles with excellent filtration performance. This solves the problems of difficult filtration and washing of colloidal tungstic acid, while significantly reducing rhenium adsorption and entrainment losses, achieving preliminary and efficient separation of tungsten and rhenium. The method provided by this invention differs from the existing alkaline route in which tungsten is retained in solution in anionic form, and also differs from the existing acidic route in which colloidal tungstic acid is precipitated due to slow acidification or natural cooling. By combining acidic synergistic oxidation leaching with rapid quantitative acidification precipitation of tungsten, the method achieves efficient separation and simultaneous recovery of tungsten and rhenium under mild acidic conditions.

[0025] 2. Compared with existing technologies, this invention achieves precise control over the crystal morphology of tungstic acid through rapid quantitative acidification. This not only optimizes the precipitation morphology of tungstic acid, avoiding colloidal formation and resolution problems, but also simultaneously improves the purity and recovery rate of both tungsten and rhenium products. The rhenium-containing filtrate is subjected to dynamic adsorption with anion exchange resin and elution with ammonia to directly obtain an ammonium perrhenate solution. After evaporation, concentration, and crystallization, ammonium perrhenate crystals are obtained. This process extracts rhenium from low-impurity filtrate, avoiding the problem of incomplete separation caused by competitive adsorption of multiple anions. The tungstic acid filter cake is washed and dried to obtain high-purity tungstic acid product. This invention integrates leaching, tungsten precipitation, and rhenium extraction into a continuous operation, significantly simplifying the process, achieving a high overall recovery rate, and ensuring product purity meets high-end application standards. It not only achieves complete separation and high recovery rate of tungsten and rhenium but also avoids the complex operation and high energy consumption problems associated with strong alkaline systems or high-temperature pyrometallurgical methods, demonstrating significant technical advantages and promising prospects for industrial application. Detailed Implementation

[0026] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a method for recovering tungsten and rhenium from tungsten-rhenium alloy waste, comprising the following steps: Step 1: Pre-treat the tungsten-rhenium alloy waste to obtain pre-treated waste fragments; Step 2: Place the pretreated waste fragments in a mixed solution of dilute hydrochloric acid and hydrogen peroxide, and carry out a leaching reaction under heating and stirring conditions to oxidize the tungsten and rhenium in the waste into tungstate ions and perrhenate ions, respectively, to obtain a mixed leachate containing tungstate and perrhenate ions. Step 3: Add concentrated hydrochloric acid to the mixed leachate, controlling the amount of concentrated hydrochloric acid added to be 5-15 mL per 100 mL of mixed leachate, so that tungsten precipitates out in the form of crystalline tungstic acid. After solid-liquid separation, crystalline tungstic acid filter cake and rhenium-containing filtrate are obtained, thereby achieving the separation of tungsten and rhenium. Step 4: The rhenium-containing filtrate is dynamically adsorbed through an anion exchange resin to load perrhenate ions onto the resin. Step 5: Elute the rhenium-loaded resin with an ammonia solution and collect the eluent to obtain an ammonium perrhenate solution; Step 6: Wash and dry the tungstic acid filter cake to obtain the tungstic acid product; Step 7: The ammonium perrhenate solution is evaporated, concentrated, and crystallized to obtain ammonium perrhenate crystals.

[0028] In a preferred embodiment, the method for recovering tungsten and rhenium from tungsten-rhenium alloy waste includes the following steps: Step 1: Pre-treat the tungsten-rhenium alloy waste to obtain pre-treated waste fragments; Step 2: Add the pretreated waste fragments to a mixed solution composed of dilute hydrochloric acid and hydrogen peroxide, and carry out a leaching reaction under heating and stirring conditions to oxidize and dissolve the tungsten and rhenium in the waste, thereby obtaining a mixed leachate containing tungstate and perrhenate. Step 3: Add concentrated hydrochloric acid to the mixed leachate until no more yellow crystalline tungstic acid precipitates. After the leachate is cooled to room temperature, filter it to obtain tungstic acid filter cake and rhenium-containing filtrate. The amount of concentrated hydrochloric acid added is 5-15 mL per 100 mL of mixed leachate. Step 4: The rhenium-containing filtrate is dynamically adsorbed through an anion exchange resin. The perrhenate anions in the filtrate exchange with the chloride ions on the resin and are loaded onto the resin. The feeding is stopped after the resin shows breakthrough. Step 5: Dynamically elute the rhenium-loaded resin with an ammonia solution. Perrhenate ions combine with ammonia to form ammonium perrhenate, which enters the liquid phase. Collect the eluent to obtain an ammonium perrhenate solution. Step 6: Wash and dry the tungstic acid filter cake to obtain the tungstic acid product; Step 7: Evaporate and concentrate the ammonium perrhenate solution to crystallize and obtain ammonium perrhenate crystals.

[0029] Preferably, the pretreatment in step 1 includes: crushing the tungsten-rhenium alloy waste and passing it through a 10-20 mesh sieve, then ultrasonically cleaning it in anhydrous ethanol for 15-30 minutes, and finally drying it at 80-100℃ for 2-4 hours.

[0030] Specifically, the ultrasonic cleaning time can be any one of 15 min, 18 min, 20 min, 22 min, 25 min, 28 min, 30 min, or a range between two of these; the drying temperature can be any one of 80℃, 85℃, 90℃, 95℃, 100℃, or a range between two of these; and the drying time can be any one of 2 h, 2.5 h, 3 h, 3.5 h, 4 h, or a range between two of these.

[0031] Preferably, the ultrasonic cleaning uses an ultrasonic frequency of 30-50kHz and an ultrasonic power of 200-300W.

[0032] Preferably, in step 2, the mixed solution is composed of dilute hydrochloric acid and hydrogen peroxide mixed in a volume ratio of (1-2):1.

[0033] Preferably, the concentration of the dilute hydrochloric acid is 0.5-1.5 mol / L, and the concentration of the hydrogen peroxide is 25-35 wt%.

[0034] Specifically, the concentration of the dilute hydrochloric acid can be any one of 0.5 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.5 mol / L, or a range between two of these; the concentration of the hydrogen peroxide can be any one of 25 wt%, 28 wt%, 30 wt%, 33 wt%, 35 wt%, or a range between two of these.

[0035] Preferably, in step 2, the liquid-to-solid ratio of the mixed solution to the waste fragments is (3-7):1mL / g.

[0036] Specifically, the liquid-to-solid ratio of the mixed solution to the waste fragments can be any one of 3:1 mL / g, 4:1 mL / g, 5:1 mL / g, 6:1 mL / g, 7:1 mL / g, or a range between two of them.

[0037] Preferably, in step 2, the leaching temperature is 80-95℃, the leaching time is 1-3h, and the stirring rate is 200-400r / min.

[0038] Specifically, the leaching temperature can be any one of 80℃, 85℃, 90℃, 95℃ or a range between two of them; the leaching time can be any one of 1h, 1.5h, 2h, 2.5h, 3h or a range between two of them; and the stirring rate can be any one of 200r / min, 250r / min, 300r / min, 350r / min, 400r / min or a range between two of them.

[0039] Specifically, in step 3, the amount of concentrated hydrochloric acid added can be any one of 5 mL, 8 mL, 10 mL, 12 mL, or 15 mL per 100 mL of mixed leachate, or a range between both.

[0040] Preferably, in step 3, the concentration of the concentrated hydrochloric acid is 36-38 wt%.

[0041] Specifically, the concentration of the concentrated hydrochloric acid can be any one of 36wt%, 37wt%, 38wt%, or a range between two of them.

[0042] Preferably, in step 4, the anion exchange resin is a chlorinated strong basic styrene-based anion exchange resin; and the flow rate of the rhenium-containing filtrate through the column is 1-3 BV / h.

[0043] Specifically, the flow rate of the rhenium-containing filtrate through the column can be any one of 1 BV / h, 1.5 BV / h, 2 BV / h, 2.5 BV / h, 3 BV / h, or a range between two of them.

[0044] Preferably, in step 5, before adsorption, the resin is washed with water, and the amount of water used for washing is 1-2 BV.

[0045] Specifically, the washing water volume can be any one of 1BV, 1.5BV, 2BV, or a range between two of them.

[0046] Preferably, in step 5, the concentration of the ammonia solution is 5-12 wt%; the elution flow rate is 0.5-2 BV / h; and the amount of ammonia solution used is 2-3 BV.

[0047] Specifically, the concentration of the ammonia solution can be any one of 5wt%, 8wt%, 10wt%, 12wt%, or a range between two of these; the elution flow rate can be any one of 0.5BV / h, 1BV / h, 1.5BV / h, 2BV / h, or a range between two of these; and the amount of ammonia solution used can be any one of 2BV, 2.5BV, 3BV, or a range between two of these.

[0048] Preferably, in step 6, the tungstic acid filter cake is first washed with dilute hydrochloric acid 2-3 times, then rinsed with deionized water 2-3 times, and then dried at 120-150℃ for 4-6 hours.

[0049] Specifically, the drying temperature can be any one of 120℃, 130℃, 140℃, 150℃ or a range between two of them, and the drying time can be any one of 4h, 4.5h, 5h, 5.5h, 6h or a range between two of them.

[0050] Preferably, in step 7, the evaporation, concentration, and crystallization temperature is 120-150℃, and the evaporation, concentration, and crystallization time is 4-6 hours.

[0051] Specifically, the evaporation, concentration, and crystallization temperature can be any one of 120℃, 130℃, 140℃, and 150℃ or a range between two of them, and the evaporation, concentration, and crystallization time can be any one of 4h, 4.5h, 5h, 5.5h, and 6h or a range between two of them.

[0052] The water used in the embodiments and comparative examples of this invention is deionized water.

[0053] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0054] Example 1 A method for recovering tungsten and rhenium from tungsten-rhenium alloy waste includes the following steps: Step 1: First, crush the tungsten-rhenium alloy waste and pass it through a 10-mesh sieve to obtain waste fragments. Then, place the waste fragments in anhydrous ethanol and ultrasonically clean them for 20 minutes at an ultrasonic frequency of 40kHz and an ultrasonic power of 250W. Finally, dry them at 90℃ for 3 hours to obtain pre-treated waste fragments. Step 2: Take the pretreated waste fragments obtained in Step 1 and add them to a mixed solution composed of 1.0 mol / L dilute hydrochloric acid and 30 wt% hydrogen peroxide in a volume ratio of 1:1. The liquid-solid ratio of the mixed solution to the waste fragments is 5:1 mL / g. Then, leach the waste fragments at a temperature of 90℃ and a stirring rate of 300 r / min for 2 hours to oxidize and dissolve the tungsten and rhenium in the waste, thus obtaining a mixed leachate containing tungstate and perrhenate. Step 3: Add concentrated hydrochloric acid with a concentration of 37wt% to the mixed leachate obtained in Step 2 until no more yellow crystalline tungstic acid precipitates. After the leachate is cooled to room temperature, filter it to obtain tungstic acid filter cake and rhenium-containing filtrate. The amount of concentrated hydrochloric acid added is 10mL per 100mL of mixed leachate. Step 4: The rhenium-containing filtrate obtained in Step 3 is dynamically adsorbed through a chlorine-type strong base styrene-based anion exchange resin column. The perrhenate anions in the filtrate exchange with the chloride ions on the resin and are loaded onto the resin. The feed is stopped after the resin shows breakthrough. The flow rate of the filtrate through the column is controlled at 2 BV / h. Step 5: Wash the saturated resin with water to remove residual acid and soluble impurities trapped in the resin gaps. Then, use ammonia solution to dynamically elute the rhenium-loaded resin. Perrhenate ions combine with ammonia to form ammonium perrhenate, which enters the liquid phase. Collect the eluent to obtain an ammonium perrhenate solution. The washing water volume is 1.5 BV, the concentration of ammonia solution is 8 wt%, the elution flow rate is 1 BV / h, and the ammonia solution volume is 2.5 BV. Step 6: Wash the tungstic acid filter cake obtained in Step 3 twice with dilute hydrochloric acid, then rinse it twice with water, and then dry it in an oven at 130°C for 5 hours to obtain the tungstic acid product. Step 7: Evaporate and concentrate the ammonium perrhenate solution obtained in Step 5 at 130°C for 5 hours to obtain ammonium perrhenate crystals.

[0055] Example 2 A method for recovering tungsten and rhenium from tungsten-rhenium alloy waste includes the following steps: Step 1: First, crush the tungsten-rhenium alloy waste and pass it through a 10-mesh sieve to obtain waste fragments. Then, place the waste fragments in anhydrous ethanol and ultrasonically clean them for 15 minutes at an ultrasonic frequency of 40kHz and an ultrasonic power of 250W. Finally, dry them at 80℃ for 4 hours to obtain pre-treated waste fragments. Step 2: Take the pretreated waste fragments obtained in Step 1 and add them to a mixed solution composed of 0.5 mol / L dilute hydrochloric acid and 30 wt% hydrogen peroxide in a volume ratio of 1:1. The liquid-solid ratio of the mixed solution to the waste fragments is 3:1 mL / g. Then, leach the waste fragments at a temperature of 80℃ and a stirring rate of 200 r / min for 3 hours to oxidize and dissolve the tungsten and rhenium in the waste, thus obtaining a mixed leachate containing tungstate and perrhenate. Step 3: Add 37wt% concentrated hydrochloric acid to the mixed leachate obtained in Step 2 until no more yellow crystalline tungstic acid precipitates. After the leachate is cooled to room temperature, filter it to obtain tungstic acid filter cake and rhenium-containing filtrate. The amount of concentrated hydrochloric acid added is 5mL per 100mL of mixed leachate. Step 4: The rhenium-containing filtrate obtained in Step 3 is dynamically adsorbed through a chlorine-type strong base styrene-based anion exchange resin column. The perrhenate anions in the filtrate exchange with the chloride ions on the resin and are loaded onto the resin. The feed is stopped after the resin shows breakthrough. The flow rate of the filtrate through the column is controlled at 1 BV / h. Step 5: Wash the saturated resin with water to remove residual acid and soluble impurities trapped in the resin gaps. Then, use an ammonia solution to dynamically elute the rhenium-loaded resin. Perrhenate ions combine with ammonia to form ammonium perrhenate, which enters the liquid phase. Collect the eluent to obtain an ammonium perrhenate solution. The washing water volume is 1 BV, the concentration of the ammonia solution is 5 wt%, the elution flow rate is 0.5 BV / h, and the ammonia solution volume is 2 BV. Step 6: Wash the tungstic acid filter cake obtained in Step 3 twice with dilute hydrochloric acid, then rinse it twice with water, and then dry it in an oven at 120°C for 6 hours to obtain the tungstic acid product. Step 7: Evaporate and concentrate the ammonium perrhenate solution obtained in Step 5 at 120°C for 6 hours to obtain ammonium perrhenate crystals.

[0056] Example 3 A method for recovering tungsten and rhenium from tungsten-rhenium alloy waste includes the following steps: Step 1: First, crush the tungsten-rhenium alloy waste and pass it through a 10-mesh sieve to obtain waste fragments. Then, place the waste fragments in anhydrous ethanol and ultrasonically clean them for 30 minutes at an ultrasonic frequency of 40kHz and an ultrasonic power of 250W. Finally, dry them at 100℃ for 2 hours to obtain pre-treated waste fragments. Step 2: Take the pretreated waste fragments obtained in Step 1 and add them to a mixed solution composed of 1.5 mol / L dilute hydrochloric acid and 30 wt% hydrogen peroxide in a volume ratio of 1:1. The liquid-solid ratio of the mixed solution to the waste fragments is 7:1 mL / g. Then, leach the waste fragments at a temperature of 95℃ and a stirring rate of 400 r / min for 1 hour to oxidize and dissolve the tungsten and rhenium in the waste, thus obtaining a mixed leachate containing tungstate and perrhenate. Step 3: Add concentrated hydrochloric acid with a concentration of 37wt% to the mixed leachate obtained in Step 2 until no more yellow crystalline tungstic acid precipitates. After the leachate is cooled to room temperature, filter it to obtain tungstic acid filter cake and rhenium-containing filtrate. The amount of concentrated hydrochloric acid added is 15mL per 100mL of mixed leachate. Step 4: The rhenium-containing filtrate obtained in Step 3 is dynamically adsorbed through a chlorine-type strong base styrene-based anion exchange resin column. The perrhenate anions in the filtrate exchange with the chloride ions on the resin and are loaded onto the resin. The feed is stopped after the resin shows breakthrough. The flow rate of the filtrate through the column is controlled at 3 BV / h. Step 5: Wash the saturated resin with water to remove residual acid and soluble impurities trapped in the resin gaps. Then, use an ammonia solution to dynamically elute the rhenium-loaded resin. Perrhenate ions combine with ammonia to form ammonium perrhenate, which enters the liquid phase. Collect the eluent to obtain an ammonium perrhenate solution. The washing water volume is 2 BV, the concentration of the ammonia solution is 12 wt%, the elution flow rate is 2 BV / h, and the ammonia solution volume is 3 BV. Step 6: Wash the tungstic acid filter cake obtained in Step 3 with dilute hydrochloric acid 3 times, then rinse it with water 3 times, and then put it in an oven to dry at 150°C for 4 hours to obtain the tungstic acid product. Step 7: Evaporate and concentrate the ammonium perrhenate solution obtained in Step 5 at 150°C for 4 hours to obtain ammonium perrhenate crystals.

[0057] Comparative Example 1 A method for recovering tungsten and rhenium from tungsten-rhenium alloy waste differs from Example 1 only in step 3, which is as follows: The mixed leachate obtained in step 2 was allowed to cool naturally and stand until no more yellow crystalline tungstic acid precipitated. After filtration, tungstic acid filter cake and rhenium-containing filtrate were obtained.

[0058] Comparative Example 2 A method for recovering tungsten and rhenium from tungsten-rhenium alloy waste differs from Example 1 only in that the amount of concentrated hydrochloric acid added in step 3 is 30 mL per 100 mL of mixed leachate.

[0059] The tungsten recovery rate, tungstic acid purity, rhenium recovery rate, and ammonium perrhenate purity of Examples 1-3 and Comparative Examples 1-2 of the present invention were tested, and the test results are shown in Table 1 below. The formula for calculating the tungsten recovery rate is as follows: Tungsten recovery rate (%) = Tungsten content in tungstic acid / Tungsten content in waste fragments × 100%; The formula for calculating the rhenium recovery rate is as follows: Rhenium recovery rate (%) = Rhenium content in ammonium perperurate / Rhenium content in waste fragments × 100%.

[0060] Table 1 As shown in Table 1, Examples 1-3, using the acidic synergistic oxidation leaching combined with quantitative acidification to control crystal morphology provided by the present invention, achieved a tungsten recovery rate of 92.1-96.3%, a tungstic acid purity of ≥98.4%, a rhenium recovery rate of 96.5-98.8%, and an ammonium perrhenate purity of ≥98.2%.

[0061] Comparative Example 1 used a natural cooling and settling method to precipitate tungstic acid without rapid quantitative acidification control. The resulting tungstic acid was in a gel-like state, resulting in slow filtration, easy filter breakage, and difficult washing. Its tungsten recovery rate was only 85.2%, tungstic acid purity was only 93.3%, rhenium recovery rate was only 86.7%, and ammonium perrhenate purity was only 91.5%. These results indicate that in an acidic system, if acidification is carried out slowly and uncontrolled, tungstic acid will precipitate in a colloidal state. The colloidal particles have a large specific surface area and abundant surface charge, which will adsorb a large amount of perrhenate ions and soluble impurities in the solution, leading to a decrease in the purity of the tungsten product and the loss of rhenium due to co-precipitation with tungstic acid. Furthermore, impurities in the filtrate compete for resin adsorption sites, further reducing the recovery rate and purity of rhenium.

[0062] Comparative Example 2 increased the amount of concentrated hydrochloric acid added to 30 mL per 100 mL of mixed leachate, exceeding the quantitative range of 5-15 mL described in this invention. The tungsten recovery rate was 88.5%, and the rhenium recovery rate was 91.8%, both lower than in Example 1. Furthermore, the purity of tungstic acid and ammonium perrhenate decreased compared to Example 1. These results indicate that while excessive acidification may yield crystalline tungstic acid, some tungstic acid undergoes resolution under strongly acidic conditions, and excessive Cl... - Rhenium competes with perrhenate for resin adsorption sites, leading to a decrease in rhenium adsorption efficiency and affecting product purity.

[0063] In summary, the tungsten recovery rate and rhenium recovery rate of Examples 1-3 of the present invention are significantly better than those of Comparative Examples 1 and 2. The purity of tungstic acid and ammonium perrhenate are also significantly higher than those of Comparative Examples 1 and 2. This indicates that the technical solution of combining acidic synergistic oxidation leaching with quantitative acidification to control crystal morphology can effectively solve the problem of rhenium adsorption and entrainment by colloidal tungstic acid, and achieve efficient separation and high-purity recovery of tungsten and rhenium.

[0064] In summary, this invention provides a method for recovering tungsten and rhenium from tungsten-rhenium alloy waste. It employs an acidic synergistic oxidation system composed of dilute hydrochloric acid and hydrogen peroxide for efficient leaching of the waste. Subsequently, by quantitatively controlling the addition of concentrated hydrochloric acid, tungsten selectively precipitates as easily filterable crystalline tungstic acid, fundamentally solving the filtration difficulties and rhenium adsorption / entrainment problems caused by the formation of colloidal tungstic acid in traditional acidic tungsten precipitation processes. Then, rhenium is efficiently recovered from the rhenium-containing filtrate through anion exchange and elution steps, ultimately obtaining high-purity tungstic acid and ammonium perrhenate products. Compared to existing technologies, this invention features a simple and efficient process, achieving complete separation and high recovery rates of tungsten and rhenium under mild conditions. It also avoids the complex operations and high energy consumption associated with strong alkaline systems or high-temperature pyrometallurgical methods, demonstrating significant technical advantages and promising prospects for industrial application.

[0065] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for recovering tungsten and rhenium from tungsten-rhenium alloy waste, characterized in that, Includes the following steps: Step 1: Pre-treat the tungsten-rhenium alloy waste to obtain pre-treated waste fragments; Step 2: Place the pretreated waste fragments in a mixed solution of dilute hydrochloric acid and hydrogen peroxide, and carry out a leaching reaction under heating and stirring conditions to oxidize the tungsten and rhenium in the waste into tungstate ions and perrhenate ions, respectively, to obtain a mixed leachate containing tungstate and perrhenate ions. Step 3: Add concentrated hydrochloric acid to the mixed leachate, controlling the amount of concentrated hydrochloric acid added to be 5-15 mL per 100 mL of mixed leachate, so that tungsten precipitates out in the form of crystalline tungstic acid. After solid-liquid separation, crystalline tungstic acid filter cake and rhenium-containing filtrate are obtained, thereby achieving the separation of tungsten and rhenium. Step 4: The rhenium-containing filtrate is dynamically adsorbed through an anion exchange resin to load perrhenate ions onto the resin. Step 5: Elute the rhenium-loaded resin with an ammonia solution and collect the eluent to obtain an ammonium perrhenate solution; Step 6: Wash and dry the tungstic acid filter cake to obtain the tungstic acid product; Step 7: The ammonium perrhenate solution is evaporated, concentrated, and crystallized to obtain ammonium perrhenate crystals.

2. The method according to claim 1, characterized in that, The pretreatment in step 1 includes: crushing the tungsten-rhenium alloy waste and passing it through a 10-20 mesh sieve, then ultrasonically cleaning it in anhydrous ethanol for 15-30 minutes, and finally drying it at 80-100℃ for 2-4 hours.

3. The method according to claim 1, characterized in that, In step 2, the mixed solution is composed of dilute hydrochloric acid and hydrogen peroxide mixed in a volume ratio of (1-2):1, the concentration of the dilute hydrochloric acid is 0.5-1.5 mol / L, and the concentration of the hydrogen peroxide is 25-35 wt%.

4. The method according to claim 1, characterized in that, In step 2, the liquid-to-solid ratio of the mixed solution to the waste fragments is (3-7):1mL / g.

5. The method according to claim 1, characterized in that, In step 2, the leaching temperature is 80-95℃, the leaching time is 1-3h, and the stirring rate is 200-400r / min.

6. The method according to claim 1, characterized in that, In step 4, before adsorption, the resin is washed with water, and the amount of water used for washing is 1-2 BV.

7. The method according to claim 1, characterized in that, In step 4, the anion exchange resin is a chlorinated strong base styrene-based anion exchange resin; the flow rate of the rhenium-containing filtrate through the column is 1-3 BV / h.

8. The method according to claim 1, characterized in that, In step 5, the concentration of the ammonia solution is 5-12 wt%; the elution flow rate is 0.5-2 BV / h; and the amount of ammonia solution used is 2-3 BV.

9. The method according to claim 1, characterized in that, In step 6, the sample is first washed 2-3 times with dilute hydrochloric acid, then rinsed 2-3 times with deionized water, and then dried at 120-150℃ for 4-6 hours.

10. The method according to claim 1, characterized in that, In step 7, the evaporation, concentration, and crystallization temperature is 120-150℃, and the evaporation, concentration, and crystallization time is 4-6 hours.

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