A method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste by using an organic solvent

Abstract

The application provides a method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste by using an organic solvent, and the method comprises the following steps: dissolving the molybdenum-rhenium alloy waste after high-temperature calcination by using ammonia water to obtain a mixed solution containing ammonium molybdate and ammonium rhenate, the concentration of molybdenum in the mixed solution is 10-100 g / L, and the concentration of rhenium is 3-60 g / L; dropping the mixed solution containing ammonium molybdate and ammonium rhenate into an organic solvent, and stirring at a stirring speed of 100-400 rpm during dropping to obtain a solid-liquid mixture; filtering the solid-liquid mixture to obtain ammonium heptamolybdate solid and a filtrate containing ammonium rhenate, drying the ammonium heptamolybdate solid to obtain product ammonium heptamolybdate; and crystallizing and filtering the filtrate containing ammonium rhenate, and drying the filter cake to obtain product ammonium rhenate. The method adopts a physical crystallization separation mechanism instead of a chemical precipitation separation mechanism, avoids the introduction of foreign ions, and has the advantages of simple process, fast separation speed, large separation coefficient, safety and environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal hydrometallurgical technology, and relates to molybdenum and rhenium, specifically to a method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents. Background Technology

[0002] Molybdenum-rhenium alloys possess excellent high-temperature performance and corrosion resistance. Currently, the separation and recycling of molybdenum-rhenium alloy waste mainly employs two major technical routes: a combined pyrometallurgical oxidation roasting-wet purification process and a fully wet process (acid leaching / alkali leaching-solvent extraction / ion exchange).

[0003] The combined pyrometallurgical oxidation roasting-wet purification process integrates the efficient pre-separation of pyrometallurgical processes with the deep purification of wet processes. It is a mainstream and mature technology for treating molybdenum-rhenium alloy waste with high rhenium content (Re > 1%), and is widely used in aerospace and high-temperature alloy recycling. The core process is as follows: First, pyrometallurgical pre-separation: Rhenium is volatilized as Re₂O₇ through oxidative roasting (500–700℃), initially separating 80%–90% of the rhenium, while molybdenum remains in the roasting residue as MoO₃. Second, wet purification: The volatilized Re₂O₇ is condensed and dissolved in dilute ammonia to obtain crude ammonium perrhenate solution, which is then removed by solvent extraction to remove residual molybdenum impurities. The roasting residue is dissolved in alkaline leaching (NaOH solution) to obtain sodium molybdate solution, which is then purified by crystallization or precipitation (e.g., adding ammonium nitrate to generate ammonium paramolybdate).

[0004] The all-wet process (acid leaching / alkali leaching-solvent extraction / ion exchange) completes the separation entirely in the liquid phase, eliminating the need for high-temperature calcination. It is more suitable for molybdenum and rhenium waste with low rhenium content (Re < 1%) or containing complex impurities (such as Al, Ti, W), and has mature applications in electronic waste and catalyst recycling. The core process of the all-wet process is as follows (taking alkali leaching-ion exchange as an example): First, alkali leaching dissolution: The waste is placed in a NaOH solution with NaNO3 added as an oxidant, and heated (80–100℃) to convert molybdenum and rhenium into MoO4, respectively. 2- and ReO4 - The first step is to introduce the solution; the second step is purification and impurity removal: filtration removes insoluble impurities (such as Fe and Cu oxides) to obtain a mixed alkaline solution containing Mo and Re; the third step is selective separation: ReO4 is adsorbed using a strongly basic anion exchange resin (such as 201×7). - (Adsorption priority is higher than MoO4) 2-The effluent is a pure sodium molybdate solution; the resin is then eluted with dilute nitric acid to obtain a high-purity rhenium solution. US Patent US3681016A discloses a method for recovering rhenium and molybdenum from solution. This method uses an amine solvent to extract soluble molybdenum and rhenium, followed by back-extraction with ammonia to obtain a mixed solution of ammonium molybdate and ammonium rheniumate. Recovery is carried out stepwise: first, the product containing molybdenum is evaporated and crystallized, and then rhenium is extracted and recovered from the crystallization mother liquor. For example, Meng Hanqi et al. from the Northwest Nonferrous Metals Research Institute, in their paper "Recovering Rhenium from High-Temperature Alloy Waste by Alkali Melting-Water Immersion Method," utilize molten oxidation to convert rhenium into water-soluble rhenium salts, while nickel, cobalt, iron, chromium, etc., form insoluble oxides. Solid-liquid separation separates rhenium from the base metal, followed by wet purification to achieve rhenium-molybdenum-tungsten separation, thus realizing the separation and recovery of rhenium.

[0005] In recent years, molybdenum-rhenium separation technology has been developing towards cleaner and more efficient methods. However, existing technologies still have some shortcomings: the pyrometallurgical oxidative roasting process requires strict temperature control; if the roasting temperature exceeds 700℃, MoO3 will volatilize along with Re2O7, leading to an increase in molybdenum impurities in the rhenium product; Re2O7 is a highly toxic volatile substance, requiring a high-efficiency condensation and recovery system, which imposes high environmental protection requirements; for low-rhenium-content waste (Re < 0.5%), the pyrometallurgical volatilization efficiency is low, resulting in poor economic efficiency. Although the all-wet process avoids high-temperature operation, it suffers from high reagent consumption, a long process time (requiring multiple steps such as dissolution, purification, separation, and extraction / ion exchange, taking 48–72 hours), easy saturation of resins or extractants for high-rhenium waste, frequent regeneration required, and low efficiency. Therefore, there is an urgent need to develop a simple, efficient, environmentally friendly, and economical new technology for molybdenum-rhenium separation. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents, thereby solving the technical problem that it is difficult to simultaneously improve the separation efficiency and the environmental friendliness of the separation operation when separating molybdenum and rhenium from molybdenum-rhenium alloy waste in the existing technology.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0008] A method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using an organic solvent, the method comprising the following steps.

[0009] Step 1: Ammonia dissolution.

[0010] The molybdenum-rhenium alloy waste was calcined at high temperature and then dissolved in ammonia water to obtain a mixed solution containing ammonium molybdate and ammonium rhenium. The pH of the mixed solution was 7.0 to 8.3, the molybdenum concentration was 10 to 100 g / L, and the rhenium concentration was 3 to 60 g / L.

[0011] Step two, precipitation separation.

[0012] Add the mixed solution containing ammonium molybdate and ammonium rhenium obtained in step one to an organic solvent. The volume of the organic solvent is 1 to 20 times the volume of the mixed solution containing ammonium molybdate and ammonium rhenium obtained in step one. Stir at a stirring speed of 100 to 400 rpm for 5 to 30 minutes to obtain a solid-liquid mixture.

[0013] The organic solvents include one or more of methanol, ethanol, isopropanol, n-propanol, ethylene glycol, acetone, butanone, tetrahydrofuran, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, and acetonitrile.

[0014] Step 3: Filtration and separation.

[0015] The solid-liquid mixture obtained in step two is filtered to obtain ammonium heptamolybdate solid and filtrate containing ammonium rhenium. The ammonium heptamolybdate solid is dried to obtain the product ammonium heptamolybdate.

[0016] Step four: crystallization.

[0017] The filtrate containing ammonium perrylate obtained in step three is crystallized to precipitate ammonium perrylate solid, which is then filtered. The filtered filter cake is dried to obtain the product ammonium perrylate.

[0018] The present invention also has the following technical features.

[0019] Specifically, in step one, the concentration of molybdenum is 18.2–48.5 g / L, and the concentration of rhenium is 10.3–35.2 g / L.

[0020] Specifically, in step two, the volume of the organic solvent is 1.6 to 3 times the volume of the mixed solution containing ammonium molybdate and ammonium perlite obtained in step one.

[0021] In step two, the stirring speed is 200-350 rpm and the stirring time is 15-30 min.

[0022] In step two, the organic solvent includes one or more of methanol, ethanol, isopropanol, and N,N-dimethylformamide.

[0023] The organic solvent is an anhydrous organic solvent.

[0024] Specifically, in step two, the method for adding the mixed solution containing ammonium molybdate and ammonium perlite from step one to the organic solvent is dropwise addition at a rate of 0.1–30 mL / min.

[0025] Specifically, in step three, the drying temperature is 45–60°C, and the drying time is 30–120 minutes.

[0026] Specifically, in step four, the temperature during crystallization is 60–90°C.

[0027] Specifically, in step four, the drying temperature is 30–80°C and the drying time is 30–180 min.

[0028] Compared with the prior art, the present invention has the following technical effects.

[0029] (I) The organic solvent used in the method of the present invention is an organic solvent that is miscible with water in any proportion. Ammonium molybdate has extremely low solubility in the organic solvent, while ammonium rhenium has relatively high solubility in the organic solvent. During the mixing process of the mixed solution containing ammonium molybdate and ammonium rhenium with the organic solvent, ammonium molybdate rapidly precipitates due to its rapidly decreasing solubility, while ammonium rhenium remains in the solution. After filtration, the efficient separation of ammonium molybdate and ammonium rhenium is achieved. This method adopts a separation mechanism of physical crystallization rather than chemical precipitation, which avoids the introduction of foreign ions. The process is simple, the separation speed is fast, the separation coefficient is large, and it is safe and environmentally friendly.

[0030] (II) The method of the present invention has a fast separation speed, a simplified process flow, and a processing time that is shortened from the traditional 48-72 hours to within 24 hours. It has a short processing time, low energy consumption, and is suitable for the efficient recycling and treatment of various molybdenum-rhenium alloy wastes.

[0031] (III) The method of the present invention can achieve a recovery rate of over 93% for molybdenum and rhenium, a product purity of over 98%, and a separation coefficient of over 80. The large separation coefficient of molybdenum and rhenium ensures product quality.

[0032] (IV) The method of the present invention has low equipment requirements, is easy to operate, and does not require a complex condensation recovery system and extraction equipment.

[0033] (V) The method of the present invention consumes less reagents and has a lower cost, which reduces the use of a large amount of reagents compared with traditional extraction processes.

[0034] (VI) The method of the present invention has wide applicability and can process various molybdenum-rhenium alloy wastes such as electronic waste, waste catalysts and single crystal blades of aero-engines that are commonly used in the prior art, and has good prospects for industrial application. Attached Figure Description

[0035] Figure 1 This is a scanning electron microscope image of ammonium heptamolybdate, the product from Example 1.

[0036] Figure 2(a) is a scanning electron microscope image of the blocky granular portion of ammonium heptamolybdate product in Example 1.

[0037] Figure 2(b) is the energy spectrum test diagram corresponding to Figure 2(a).

[0038] Figure 3(a) is a scanning electron microscope image of the flaky particles of ammonium heptamolybdate in Example 1.

[0039] Figure 3(b) is the energy spectrum test diagram corresponding to Figure 3(a).

[0040] Figure 4 This is a scanning electron microscope image of ammonium heptamolybdate, the product from Example 4, at a magnification of 200x.

[0041] Figure 5(a) is a scanning electron microscope image of ammonium heptamolybdate product in Example 4 under a 25 μm scale.

[0042] Figure 5(b) is the energy spectrum test diagram corresponding to Figure 5(a).

[0043] Figure 6 The X-ray diffraction pattern of ammonium heptamolybdate, the product in Example 4.

[0044] Figure 7 This is a scanning electron microscope image of ammonium perrylate, the product from Example 4.

[0045] The specific content of the present invention will be further described in detail below with reference to the embodiments. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, all the equipment, raw materials and methods in this invention are commonly used in the art and are known in the prior art. For example, the Buchner funnel is a known Buchner funnel, the oven is a known oven, and the energy dispersive spectroscopy test method is a known test method.

[0047] In this invention, the separation mechanism of ammonium heptamolybdate and ammonium rheniumate is as follows: Ammonium heptamolybdate (also known as ammonium paramolybdate (NH4)6Mo7O) 24 The core reason why this strongly ionic polymolybdate is insoluble in organic solvents such as methanol and ethanol is that the solvent polarity and solvation ability cannot meet the dissolution requirements of ionic compounds. The specific mechanism is as follows: First, the ionic structure characteristics of ammonium heptamolybdate: Ammonium heptamolybdate crystals consist of positively charged NH4+ ions. + With highly negatively charged polymolybdate Mo7O 24 6- Formed by strong ionic bonds, the ions exhibit extremely strong Coulomb attraction, requiring highly polar solvents to disrupt their ionic lattice and achieve dissociation.

[0048] Second, organic solvents have insufficient solvation ability: the dielectric constants of methanol and ethanol (methanol≈33, ethanol≈24) are much lower than those of water (≈80), and their polarity is weak, so they cannot effectively shield NH4. + With Mo7O 24 6-The strong electrostatic interaction between them makes it difficult to dissociate the ionic bonds of ammonium heptamolybdate. Meanwhile, methanol and ethanol molecules contain hydrophobic hydrocarbon groups (-CH3, -C2H5) and have a limited number of hydroxyl groups (-OH), resulting in weak solvation ability and making them unable to react with NH4+. + Mo7O 24 6- A stable solvation layer is formed, making it impossible to stably disperse ions in the solvent system.

[0049] Third, the thermodynamic properties of dissolution equilibrium: Ammonium heptamolybdate has a positive Gibbs free energy for ion dissociation and solvation processes in organic solvents such as methanol and ethanol, and the dissolution process cannot proceed spontaneously, so it is almost insoluble in these organic solvents.

[0050] Unlike ammonium heptamolybdate, which is insoluble, ammonium rheniumate (NH4ReO4) is soluble in organic solvents such as methanol and ethanol. The core reason for this lies in the compatibility between its ionic structure and solvation ability, and the specific mechanism is as follows: First, the ionic structure characteristics of ammonium perrylate: Ammonium perrylate crystals are composed of NH4+. + With perrhenate ReO4 - Formed through ionic bonding, ReO4 differs from the highly negatively charged polymolybdate ions of ammonium heptamolybdate. - It has a single tetrahedral structure, carries only a -1 negative charge, has a large ionic radius and low charge density, making NH4+... + With ReO4 - The Coulomb attraction between them is significantly weaker than the interaction between ions in ammonium heptamolybdate, and the ionic lattice is more easily dissociated by organic solvents.

[0051] Second, the solvation compatibility of organic solvents: Although methanol and ethanol are less polar than water, ReO4 - Its low charge density reduces the requirement for solvent polarity, and its tetrahedral structure can form weak hydrogen bond interactions with the hydroxyl groups (-OH) in methanol and ethanol molecules. Meanwhile, NH4+... + It can also form hydrogen bonds with the hydroxyl groups of solvent molecules. The two work together to form a stable solvation layer, which stably disperses the dissociated ions in the organic solvent system.

[0052] Third, the thermodynamic properties of dissolution equilibrium: Ammonium rhenium oxide exhibits negative Gibbs free energies for ion dissociation and solvation processes in methanol and ethanol, allowing for spontaneous dissolution. Furthermore, ReO4... - Its stable structure and resistance to hydrolysis under a wide range of conditions further ensure its solubility in organic solvents, which is also the key thermodynamic factor for the difference in solubility between ammonium perrylate and ammonium heptamolybdate.

[0053] In summary, molybdate and rhenium ions are highly soluble in a good solvent (water). In a pure water environment with a pH of 7.0–8.5, molybdenum exists as MoO4.2 The main component is a solvent that is miscible with water, has extremely poor solubility for ammonium molybdate but strong solubility for ammonium rheniumate (such as ethanol, methanol, acetone, etc.). The molybdate group then undergoes a polymerization reaction: 7MoO4 2 +8H + [Mo7O 24 ] 6 With the addition of 4H₂O, the water activity and solvent dielectric constant of the system decrease, shifting the molybdate polymerization region towards alkalinity, moving the equilibrium to the right, and making molybdenum more readily polymerized. Simultaneously, the decrease in water content enhances the stability of polymolybdate, causing molybdate ions to aggregate into heptamolybdate ions, which precipitate out. The organic solvent significantly reduces the solubility of ammonium heptamolybdate; once formed, ammonium heptamolybdate crystals precipitate rapidly, further promoting the continued polymerization reaction. Therefore, in the pH range of 7–8.5, molybdate ions ultimately precipitate as ammonium heptamolybdate in this system. However, ammonium rheniumate, due to its ability to form a stable solvation layer in organic solvents such as methanol and ethanol, does not experience a significant decrease in solubility due to the decrease in polarity of the mixed solvent, and therefore does not precipitate, ultimately achieving the separation of ammonium heptamolybdate and ammonium rheniumate.

[0054] In this invention, the molybdenum-rhenium alloy waste includes one or more of the commonly known electronic waste, spent catalysts, and single-crystal blades for aero-engines.

[0055] In this invention, ammonium perrhenate is a common name for ammonium perrhenate, which is also known as perrhenate. Ammonium perrhenate is the commonly used ammonium perrhenate known in the art.

[0056] In step two of this invention, the organic solvents used in the precipitation separation are all analytical grade and all are anhydrous; the organic solvents are all commonly used organic solvents known in the art.

[0057] The ammonia water used in this invention is all analytical grade ammonia water commonly known in the art.

[0058] Following the above technical solution, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of the present invention fall within the protection scope of the present invention.

[0059] Example 1: (Anhydrous methanol as organic solvent) This embodiment provides a method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents. The method includes the following steps: Step 1: Ammonia dissolution.

[0060] The molybdenum-rhenium alloy scrap was calcined at 625℃ for 5 hours and then dissolved in 25% ammonia water to obtain a 500 mL mixed solution containing ammonium molybdate and ammonium rhenium with a pH of 7.4. The molybdenum concentration in the mixed solution was 21.77 g / L and the rhenium concentration was 20.96 g / L.

[0061] Step two, precipitation separation.

[0062] The mixed solution containing ammonium molybdate and ammonium rhenium obtained in step one was added dropwise to 1000 mL of anhydrous methanol at a rate of 10 mL / min. At the same time as the dropwise addition, the mixture was stirred at a speed of 200 rpm for 15 min. This caused the ammonium molybdate in the mixed solution from step one to precipitate due to supersaturation caused by the decrease in solubility, while the ammonium rhenium remained in a dissolved state, resulting in a solid-liquid mixture.

[0063] In this embodiment, if the concentration of ammonium molybdate solute is too high during the separation process, rhenium ions are easily entrained during precipitation, resulting in a decrease in the separation coefficient. At the same time, the stirring speed during precipitation separation should be appropriate. Adding unsuitable solvents can easily lead to nucleation. If the stirring is too slow, a large number of crystals will agglomerate, causing the mother liquor (containing rhenium ions) to be encapsulated, resulting in a low separation coefficient and uneven crystal precipitation, leading to poor separation effect.

[0064] Step 3: Filtration and separation.

[0065] The solid-liquid mixture obtained in step two was filtered using a Buchner funnel to obtain a filtrate containing ammonium rheniumate and a white solid ammonium heptamolybdate. The solid ammonium heptamolybdate was washed twice with anhydrous methanol and then dried in an oven at 55°C for 90 minutes to obtain the product ammonium heptamolybdate.

[0066] Step four: crystallization.

[0067] The filtrate containing ammonium perrylate obtained in step 3 was evaporated and crystallized in a water bath at 75°C to precipitate white ammonium perrylate solid. The solid was then filtered, and the filtered filter cake was dried at 40°C for 120 minutes to obtain the product ammonium perrylate.

[0068] In this embodiment, evaporation and crystallization are carried out at atmospheric pressure, which is 101.3 kPa.

[0069] The product ammonium heptamolybdate obtained in this embodiment was tested by scanning electron microscopy, and the results are as follows: Figure 1 As shown. From Figure 1 As can be seen from the data, the product ammonium heptamolybdate consists of blocky and flake-like particles, some of which are aggregated together, with a particle size between 10 and 200 µm. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were performed on the blocky and flake-like portions of the product ammonium heptamolybdate, respectively. The results are shown in Figures 2(a) to 3(b), and Tables 1 and 2. According to the test results, the rhenium content in the product ammonium heptamolybdate is extremely low, and the molybdenum-rhenium separation coefficient is large.

[0070] Testing revealed that the product obtained in this embodiment contained 17.32g of ammonium heptamolybdate with a purity of 98.5%; and 13.62g of ammonium rhenium with a purity of 98.2%. The recovery rate of molybdenum was 91.7%, the recovery rate of rhenium was 90.0%, and the separation coefficient between molybdenum and rhenium reached 413.

[0071] Table 1. Elemental content distribution of the granular portion of ammonium heptamolybdate product according to energy dispersive spectroscopy (EDS) analysis. element Line type Apparent concentration k ratio Wt% Wt% Sigma Standard sample label Manufacturer Standards O K-line system 1.62 0.00546 46.20 0.87 <![CDATA[SiO2]]> yes Mo L-line system 1.60 0.01599 53.67 0.87 Mo yes Re M-line system 0.00 0.00004 0.13 0.38 Re yes Total 100.00 Table 2. Elemental content distribution of the flaky particles in ammonium heptamolybdate product according to energy dispersive spectroscopy (EDS) analysis. element Line type Apparent concentration k ratio Wt% Wt% Sigma Standard sample label Manufacturer Standards O K-line system 0.77 0.00260 33.09 0.87 <![CDATA[SiO2]]> yes Mo L-line system 1.58 0.01580 66.77 0.91 Mo yes Re M-line system 0.00 0.00003 0.13 0.46 Re yes Total 100.00 Example 2: (Anhydrous N,N-dimethylformamide as organic solvent) This embodiment provides a method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using an organic solvent. This method is basically the same as the method in Example 1, except that: in step two, the dropping rate is changed to 2 mL / min, the organic solvent is changed to 800 mL of anhydrous N,N-dimethylformamide, the stirring speed is changed to 350 rpm, and the stirring time is changed to 25 min; in step three, the ammonium heptamolybdate solid is changed to being rinsed twice with anhydrous ethanol, and the drying conditions are changed to drying at 60°C for 30 min; in step four, the crystallization method is changed from evaporation crystallization to vacuum distillation, the vacuum distillation temperature is 75°C and the pressure is 5.33 kPa, and the filter cake drying conditions are changed to drying at 80°C for 90 min.

[0072] The test results showed that the ammonium heptamolybdate product obtained in this embodiment totaled 17.97g with a purity of 99.2%; the ammonium rhenium product totaled 14.15g with a purity of 98.6%; the recovery rate of molybdenum was 92.1%, the recovery rate of rhenium was 93.5%, and the separation coefficient of molybdenum and rhenium reached 178.

[0073] Example 3: (The solvent obtained by mixing anhydrous methanol and anhydrous isopropanol in a volume ratio of 1:1 is used as the organic solvent) This embodiment provides a method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using an organic solvent. This method is basically the same as the method in Example 1, except that: in step one, the pH of the mixed solution containing ammonium molybdate and ammonium rhenate is changed to 8.1, and the molybdenum concentration in the mixed solution is 18.2 g / L and the rhenium concentration is 35.2 g / L; in step two, the dropping rate is changed to 5 mL / min, the organic solvent is changed to anhydrous methanol:anhydrous isopropanol with a volume ratio of 1:1, the stirring speed is changed to 220 rpm, and the stirring time is changed to 20 min; in step three, the ammonium heptamolybdate solid is changed to be washed twice with anhydrous methanol; in step four, the evaporation and crystallization temperature is changed to 80℃, and the drying conditions of the filter cake are changed to drying at 60℃ for 90 min.

[0074] Testing revealed that the product obtained in this embodiment contained 14.08 g of ammonium heptamolybdate with a purity of 98.9%; and 24.02 g of ammonium rhenium with a purity of 99.1%. The recovery rate of molybdenum was 89.3%, the recovery rate of rhenium was 94.7%, and the separation coefficient of molybdenum and rhenium reached 198.

[0075] Example 4: (Anhydrous ethanol as organic solvent) This embodiment provides a method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using an organic solvent. This method is basically the same as the method in Embodiment 1, except that: in step one, the pH of the mixed solution containing ammonium molybdate and ammonium rhenate is changed to 8.3, the molybdenum concentration in the mixed solution is 48.5 g / L, and the rhenium concentration is 10.3 g / L; in step two, the dropping rate is changed to 30 mL / min, the organic solvent is changed to 1500 mL of anhydrous ethanol, the stirring speed is changed to 280 rpm, and the stirring time is changed to 30 min; in step three, the ammonium heptamolybdate solid is changed to being rinsed twice with anhydrous ethanol, and the drying time is changed to 100 min; in step four, the evaporation and crystallization temperature is changed to 85℃, and the drying conditions of the filter cake are changed to drying at 60℃ for 90 min.

[0076] The product ammonium heptamolybdate obtained in this embodiment was tested by scanning electron microscopy, and the results are as follows: Figure 4 As shown in Figure 5(a), the product ammonium heptamolybdate is composed of flake-like and partially blocky particles, aggregated together, with uneven size and a particle size of less than 100µm. Energy dispersive spectroscopy (EDS) was performed on the ammonium heptamolybdate product obtained in this embodiment, and the results are shown in Figure 5(b) and Table 3. X-ray diffraction analysis was performed on the product obtained in step three of this embodiment, as shown in Figure 5(a). Figure 6 As shown, the product is clearly ammonium heptamolybdate. Scanning electron microscopy (SEM) analysis was performed on the ammonium rhenium obtained in this embodiment, as shown... Figure 7 As shown, the product ammonium perrylate is mainly in the form of irregular short columnar shapes, accompanied by a small amount of equiaxed block crystals.

[0077] Testing revealed that the product obtained in this embodiment contained 40.60g of ammonium heptamolybdate with a purity of 99.5%; 6.94g of ammonium rhenium with a purity of 99.3%; the recovery rate of molybdenum was 96.6%, the recovery rate of rhenium was 93.5%, and the separation coefficient of molybdenum and rhenium reached 80.9.

[0078] Table 3. Elemental content distribution corresponding to the energy dispersive spectroscopy test of ammonium heptamolybdate product.

Claims

1. A method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents, characterized in that, The method includes the following steps: Step 1, ammonia solution: The molybdenum-rhenium alloy waste was calcined at high temperature and then dissolved in ammonia water to obtain a mixed solution containing ammonium molybdate and ammonium rhenium. The pH of the mixed solution was 7.0-8.3, the molybdenum concentration was 10-100 g / L, and the rhenium concentration was 3-60 g / L. Step 2, precipitation separation: Add the mixed solution containing ammonium molybdate and ammonium rhenium obtained in step one to an organic solvent. The volume of the organic solvent is 1 to 20 times the volume of the mixed solution containing ammonium molybdate and ammonium rhenium obtained in step one. Stir at a stirring speed of 100 to 400 rpm for 5 to 30 minutes to obtain a solid-liquid mixture. The organic solvents include one or more of methanol, ethanol, isopropanol, n-propanol, ethylene glycol, acetone, butanone, tetrahydrofuran, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, and acetonitrile. Step 3, Filtration and Separation: The solid-liquid mixture obtained in step two is filtered to obtain ammonium heptamolybdate solid and filtrate containing ammonium rhenium. The ammonium heptamolybdate solid is dried to obtain the product ammonium heptamolybdate. Step 4, Crystallization: The filtrate containing ammonium perrylate obtained in step three is crystallized to precipitate ammonium perrylate solid, which is then filtered. The filtered filter cake is dried to obtain the product ammonium perrylate.

2. The method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents as described in claim 1, characterized in that, In step one, the concentration of molybdenum is 18.2–48.5 g / L, and the concentration of rhenium is 10.3–35.2 g / L.

3. The method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents as described in claim 1, characterized in that, In step two, the volume of the organic solvent is 1.6 to 3 times the volume of the mixed solution containing ammonium molybdate and ammonium perlite obtained in step one; In step two, the stirring speed is 200-350 rpm and the stirring time is 15-30 min; In step two, the organic solvent includes one or more of methanol, ethanol, isopropanol, and N,N-dimethylformamide; The organic solvent is an anhydrous organic solvent.

4. The method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents as described in claim 1, characterized in that, In step two, the mixed solution containing ammonium molybdate and ammonium perlite from step one is added to the organic solvent by dropwise addition at a rate of 0.1–30 mL / min.

5. The method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents as described in claim 1, characterized in that, In step three, the drying temperature is 45–60°C and the drying time is 30–120 minutes.

6. The method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents as described in claim 1, characterized in that, In step four, the crystallization temperature is 60–90°C.

7. The method for separating molybdenum and rhenium from molybdenum-rhenium alloy waste using organic solvents as described in claim 1, characterized in that, In step four, the drying temperature is 30–80°C and the drying time is 30–180 min.

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