Method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore

Abstract

The invention provides a method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore, which comprises the following steps: carrying out water heating saturation primary redissolution on a high-molybdenum ammonium perrhenate product needing molybdenum reduction to obtain a high-molybdenum liquid; then hydrogen peroxide and ammonia water are added, the temperature is kept at 70-75 DEG C, the pH value of the high-molybdenum liquid is larger than 10, then nanoscale cross-flow filtration is conducted, and concentrated liquid is returned to be redissolved; performing freezing crystallization on the filtered high-molybdenum clear liquid at the final temperature of 0-3 DEG C, and returning crystallization mother liquor for re-dissolution; carrying out negative pressure suction filtration on the obtained primary crystallized ammonium perrhenate by using 200-mesh filter cloth to obtain a primary crystallized ammonium perrhenate filter cake; and carrying out water saturation secondary redissolution on the obtained primary crystallized ammonium perrhenate filter cake, then adding ammonia water, carrying out freezing crystallization, and carrying out suction filtration and drying after crystallization to obtain a low-molybdenum ammonium perrhenate product. According to the method, two redissolution separation stages are set in the molybdenum and rhenium separation process, and the molybdenum removal efficiency is further guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of chemical production technology and relates to the recovery of ammonium perperurate for molybdenum removal, specifically to a method for recovering ammonium perperurate for molybdenum removal from molybdenum ore. Background Technology

[0002] Rhenium is a rare, high-melting-point metal commonly used in the aerospace industry. Because it is an indispensable element in the production of turbofan engines for aircraft engines and turbofan engines for steam turbines, it is considered a strategic element. During molybdenum smelting, rhenium is oxidized into high-valence oxides, which then sublimate into the smelting flue gas. In the pre-acidification scrubbing system, these oxides accumulate in the leachate. The recovery of ammonium perrhenate from rhenium-containing leachate primarily involves ion adsorption and concentration crystallization in the product stage. Due to the presence of large amounts of molybdate ions (molybdate has a negative monovalent valence, the same as the perrhenate ions in ammonium perrhenate) in various stages of ammonium perrhenate production, a large amount of molybdenum impurities are mixed into the final product, resulting in an excessive molybdenum content (approximately 40–200 ppmwt) in the ammonium perrhenate product. Currently, the industry standard for ammonium perrhenate 3N products (i.e., ammonium perrhenate products with a purity of ≥99.9%) requires molybdenum to be below 40 ppm wt, while ammonium perrhenate 4N products (i.e., ammonium perrhenate products with a purity of ≥99.99%) require molybdenum to be below 10 ppm wt. Existing rhenium adsorption and concentration systems cannot effectively remove this portion of molybdenum impurities, necessitating the adoption of new molybdenum removal processes. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for recovering molybdenum from molybdenum ore using ammonium perrhenate, thereby solving the technical problem that the molybdenum content in the ammonium perrhenate product during rhenium recovery in the existing technology needs to be further reduced.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A method for recovering molybdenum from ammonium perrhenate in molybdenum ore, the method comprising the following steps:

[0006] Step 1: Saturated remelting and temperature control:

[0007] For high-molybdenum perrhenate ammonium products that require molybdenum reduction, a single re-dissolution with water at elevated temperature is performed to obtain a high-molybdenum solution.

[0008] Step 2, oxidation and initial ammonia replenishment to adjust pH:

[0009] Hydrogen peroxide and ammonia were added to the high-molybdenum solution obtained in step one. The temperature of the high-molybdenum solution was 70-75℃ and the pH of the high-molybdenum solution was >10 during the operation to obtain a high-molybdenum solution after one ammonia addition.

[0010] Step 3, Nanoscale impurity removal filtration:

[0011] Under conditions of 70-75℃, the high-molybdenum solution obtained in step two after ammonia replenishment is subjected to nanoscale cross-flow filtration with a filtration precision of 50nm. After filtration, a clear high-molybdenum solution is obtained for use, and the concentrated solution is returned to step one for redissolution. The system that is saturated and redissoluted once is periodically discharged with slag.

[0012] Step 4, one-time cooling crystallization:

[0013] The high-molybdenum clear liquid obtained after filtration in step three is subjected to freeze crystallization at a final temperature of 0 to -3°C. The mother liquor is returned to step one for redissolution to obtain primary crystallized ammonium perrhenate.

[0014] Step 5, filtration and separation:

[0015] The primary crystallized ammonium perrhenate obtained in step four was subjected to negative pressure filtration using a 200-mesh filter cloth to obtain a primary crystallized ammonium perrhenate filter cake.

[0016] Step 6, Secondary Redissolution:

[0017] The primary crystallized ammonium perrhenate filter cake obtained in step five is subjected to water-saturated secondary redissolution to obtain a secondary ammonium perrhenate solution.

[0018] Step 7, Second ammonia supplementation to adjust pH:

[0019] Ammonia water is added to the secondary perrhenate ammonium solution obtained in step six, and the pH of the secondary perrhenate ammonium solution is controlled to be greater than 10. The temperature of the secondary perrhenate ammonium solution during the operation is 70-75℃, thus obtaining the secondary perrhenate ammonium ammonia replenishment solution.

[0020] Step 8, Ultrasonic-assisted secondary cooling crystallization:

[0021] The secondary ammonium perrhenate solution obtained in step seven was subjected to freeze crystallization at a final temperature of 0 to -3°C. Simultaneously, intermittent ultrasonic crystallization was used. The mother liquor was returned to step one for redissolution to obtain secondary crystallized ammonium perrhenate.

[0022] Step 9, filtration and drying:

[0023] The secondary crystallized ammonium perrhenate obtained in step eight was filtered through a 50-mesh filter cloth, and the filter cake of the secondary crystallized ammonium perrhenate was dried by microwave to obtain a low-molybdenum ammonium perrhenate product.

[0024] The present invention also has the following technical features:

[0025] Specifically, in step one, the high-molybdenum perrhenate ammonium product is the perrhenate ammonium product used for rhenium recovery from the rhenium leaching liquid of molybdenum concentrate roasting flue gas.

[0026] Specifically, in step one, the dissolution temperature is 70–75°C.

[0027] Specifically, in step two, the concentration of hydrogen peroxide is 25-30 wt.%, and the volume of hydrogen peroxide added is 0.5-2% of the volume ratio of the high molybdenum solution.

[0028] Specifically, in step two, the concentration of the ammonia water is 25-38 wt.%, and the volume of ammonia water added is 2-5% of the volume ratio of the high molybdenum solution.

[0029] Specifically, in step four, the duration of the freeze-crystallization is 12 to 24 hours.

[0030] Specifically, in step six, the dissolution temperature for saturated dissolution is 70–75°C.

[0031] Specifically, in step seven, the concentration of the ammonia water is 25-38 wt.%, and the volume of ammonia water added is 3-5% of the volume ratio of the secondary perrhenate ammonium solution.

[0032] Specifically, in step eight, the frequency of the ultrasound is 40 kHz, and the interval between ultrasound waves is once every 20 to 30 minutes.

[0033] Specifically, in step nine, the microwave drying temperature is 120°C and the drying time is 4 hours.

[0034] Compared with the prior art, the present invention has the following technical effects:

[0035] (I) In the method of the present invention, hydrogen peroxide and ammonia are used as oxidants and reacted by heating and stirring to convert molybdenum in the high molybdenum solution from a low valence state to a high valence state and convert soluble impurities into insoluble impurities.

[0036] (II) The method of the present invention uses heating to separate the insoluble impurities in the oxidized solution by cross-flow filtration at 50 nm under the high solubility of ammonium perrhenate, effectively removing the insoluble impurities oxidized and precipitated in the high molybdenum solution after one ammonia replenishment.

[0037] (III) The method in this invention utilizes the difference in solubility between rhenium and molybdenum and employs a freeze crystallization method to effectively separate molybdenum and rhenium.

[0038] (IV) The method of the present invention sets two remelting separation stages in the molybdenum and rhenium separation process, which further ensures the efficiency of molybdenum removal.

[0039] (V) The method of the present invention uses intermittent ultrasound with a frequency of 40KHz during the second remelting and separation process to prevent the enrichment of molybdenum in the secondary crystallization of ammonium perrhenate, improve the crystallization efficiency of the secondary crystallization of ammonium perrhenate, and improve the particle size of the low molybdenum ammonium perrhenate product.

[0040] (VI) The method in this invention returns the impurity-containing concentrated liquid from the nanoscale impurity removal filtration and the mother liquor from the two crystallization processes to the saturated primary redissolution system for secondary utilization. The saturated primary redissolution system is equipped with a periodic slag discharge cycle, which improves the overall recovery and utilization rate of rhenium.

[0041] (VII) The method in this invention uses microwave drying at 120°C for low temperature drying, and the moisture content of the final low molybdenum perrhenate ammonium product is less than 0.03%, which improves the drying efficiency and helps to improve the stability and storage life of the low molybdenum perrhenate ammonium product.

[0042] (VIII) The method in this invention ultimately verified that the removal rate of molybdenum impurity elements is greater than or equal to 95%. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the process flow for removing molybdenum from ammonium perrhenate products during rhenium recovery in this invention.

[0044] The specific content of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0045] It should be noted that, unless otherwise specified, all equipment, methods and raw materials in this invention are based on existing technologies. For example, the apparatus for negative pressure filtration is a known apparatus for negative pressure filtration, the nanoscale cross-flow filtration method is a known nanoscale cross-flow filtration method, the 30wt.% hydrogen peroxide is a known 30wt.% hydrogen peroxide, the molybdenum concentrate roasting flue gas scrubbing liquid is a known molybdenum concentrate roasting flue gas scrubbing liquid, and the deionized water is a known deionized water.

[0046] All ammonia and hydrogen peroxide in this invention are of analytical grade.

[0047] In this invention, ppm wt refers to one part per million of mass, for example, 7.5 ppm wt refers to seven and a half parts per million of mass.

[0048] Following the above technical solutions, 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 based on the technical solutions of this application fall within the protection scope of the present invention.

[0049] Example 1:

[0050] This embodiment provides a method for recovering molybdenum from molybdenum ore using ammonium perrhenate, such as... Figure 1 As shown, the method includes the following steps:

[0051] Step 1: Saturated remelting and temperature control:

[0052] For the 85g high-molybdenum perrhenate ammonium product that requires molybdenum reduction, 500ml of deionized water was heated to saturation and redissolved once in a beaker at a temperature of 75℃. After complete dissolution, the temperature was maintained at 75℃ to obtain a high-molybdenum solution.

[0053] In step one, the high-molybdenum perrhenate ammonium product is the perrhenate ammonium product from the rhenium recovery in the leaching liquid of molybdenum concentrate roasting flue gas, and the molybdenum content in the high-molybdenum perrhenate ammonium product is 150 ppm wt.

[0054] In this embodiment, the saturated single remelting system adopts a commonly used saturated single remelting system known in the art.

[0055] Step 2, oxidation and initial ammonia replenishment to adjust pH:

[0056] Add 5 ml of 30 wt.% hydrogen peroxide and 15 ml of 25 wt.% ammonia to the high molybdenum solution obtained in step one to make the pH of the high molybdenum solution > 10. The temperature of the high molybdenum solution during the operation is 75℃, and a high molybdenum solution after one ammonia addition is obtained.

[0057] In step two, the volume of hydrogen peroxide added is 1% of the volume of the high-molybdenum solution, and the volume of ammonia added is 3% of the volume of the high-molybdenum solution.

[0058] Step 3, Nanoscale impurity removal filtration:

[0059] At 75℃, the high-molybdenum solution obtained in step two after ammonia replenishment is subjected to nanoscale cross-flow filtration with a filtration precision of 50nm. After filtration, a clear high-molybdenum solution is obtained for later use, and the concentrated solution is returned to step one for redissolution. The system that is saturated and redissoluted once is periodically discharged with slag.

[0060] Step 4, one-time cooling crystallization:

[0061] The high-molybdenum clear liquid obtained after filtration in step three was subjected to freeze crystallization. The freeze crystallization was carried out in three stages of cooling, with the final freeze crystallization temperature being -1℃ and the freeze crystallization duration being 24 hours. The mother liquor was returned to step one for redissolution to obtain primary crystallized ammonium perrhenate.

[0062] Step 5, filtration and separation:

[0063] The primary crystallized ammonium perrhenate obtained in step four was subjected to negative pressure filtration using a 200-mesh filter cloth to obtain a primary crystallized ammonium perrhenate filter cake.

[0064] Step 6, Secondary Redissolution:

[0065] The primary crystallized ammonium perrhenate filter cake obtained in step five was subjected to a second saturated redissolution with deionized water to obtain a secondary ammonium perrhenate solution. The saturated dissolution temperature was 75°C.

[0066] Step 7, Second ammonia supplementation to adjust pH:

[0067] Add 15 ml of 25 wt.% ammonia water to the secondary ammonium perperate solution obtained in step six, control the pH of the secondary ammonium perperate solution to be greater than 10, and keep the temperature of the secondary ammonium perperate solution at 75°C during the operation to obtain the secondary ammonium perperate ammonia replenishment solution.

[0068] In step seven, the volume of ammonia added is 3% of the volume of the secondary perrhenate ammonium solution.

[0069] Step 8, Ultrasonic-assisted secondary cooling crystallization:

[0070] The secondary ammonium perrhenate solution obtained in step seven was subjected to freeze crystallization at a final temperature of -1°C. Simultaneously, intermittent ultrasonic crystallization was performed using a frequency of 40 kHz, with the ultrasonic waves intermittently every 30 minutes. The mother liquor was returned to step one for redissolution to obtain secondary crystallized ammonium perrhenate.

[0071] In this embodiment, intermittent ultrasonic-assisted crystallization can reduce the enrichment of impurities in secondary crystallized ammonium perrhenate and reduce the particle size of secondary crystallized ammonium perrhenate.

[0072] Step 9, filtration and drying:

[0073] The secondary crystallized ammonium perrhenate obtained in step eight was filtered through a 50-mesh filter cloth, and the filter cake of the secondary crystallized ammonium perrhenate was microwave-dried at 120℃ for 4 hours to obtain a low-molybdenum ammonium perrhenate product.

[0074] The molybdenum removal rate was determined to be 95% using the method in this embodiment, and the specific results are shown in Table 1.

[0075] Table 1. Molybdenum content analysis values ​​of high-molybdenum ammonium perrhenate products before and after molybdenum removal.

[0076]

[0077] Example 2:

[0078] This embodiment provides a method for recovering molybdenum from molybdenum ore using ammonium perrhenate. The method in this embodiment is basically the same as the method in Embodiment 1, except that: in step one, the mass of the high-molybdenum ammonium perrhenate product is 75g, and the molybdenum content in the high-molybdenum ammonium perrhenate product is 130ppm wt; in step two, the volume of hydrogen peroxide added is 4ml, and the volume of ammonia added is 12ml (i.e., the volume of hydrogen peroxide added is 0.8% of the volume of the high-molybdenum solution, and the volume of ammonia added is 2.4% of the volume of the high-molybdenum solution); in step four, the freezing crystallization is carried out in two stages of cooling, and the final freezing crystallization temperature is -3℃; in step seven, the volume of ammonia added is 20ml (the volume of ammonia added is 4% of the volume of the secondary ammonium perrhenate solution); in step eight, the final freezing crystallization temperature is -3℃, and the ultrasonic treatment is intermittent every 20 minutes.

[0079] The molybdenum removal rate determined using the method in this embodiment was 97.8%, and the specific results are shown in Table 2.

[0080] Table 2. Molybdenum content analysis values ​​of high-molybdenum ammonium perrhenate products before and after molybdenum removal.

[0081]

[0082] Example 3:

[0083] This embodiment provides a method for recovering molybdenum from molybdenum ore using ammonium perrhenate. The method for recovering molybdenum from molybdenum ore using ammonium perrhenate in this embodiment is basically the same as the method in Embodiment 1, except that: in step one, the mass of the high-molybdenum ammonium perrhenate product is 100g, and the molybdenum content in the high-molybdenum ammonium perrhenate product is 44ppm wt; in step two, the volume of hydrogen peroxide added is 7.5ml (i.e., the volume of hydrogen peroxide added is 1.5% of the volume of the high-molybdenum solution); in step four, the final temperature for freeze crystallization is -3℃; in step seven, the volume of ammonia added is 20ml (i.e., the volume of ammonia added is 4% of the volume of the secondary ammonium perrhenate solution); in step eight, the final temperature for freeze crystallization is -3℃, and the ultrasonic treatment is intermittent every 25 minutes.

[0084] The molybdenum removal rate was 99.8% as determined by the method in this embodiment, and the specific results are shown in Table 3.

[0085] Table 3. Molybdenum content analysis values ​​of high-molybdenum ammonium perrhenate products before and after molybdenum removal.

[0086]

Claims

1. A method for recovering molybdenum from molybdenum ore using ammonium perrhenate, characterized in that, The method includes the following steps: Step 1: Saturated remelting and temperature control: For high-molybdenum perrhenate ammonium products that require molybdenum reduction, water is heated and saturated for a single redissolution to obtain a high-molybdenum solution. Step 2, oxidation and initial ammonia replenishment to adjust pH: Add hydrogen peroxide and ammonia to the high molybdenum solution obtained in step one. The temperature of the high molybdenum solution is 70-75℃ and the pH of the high molybdenum solution is >10 during the operation to obtain a high molybdenum solution after one ammonia addition. Step 3, Nanoscale impurity removal filtration: Under conditions of 70-75℃, the high-molybdenum solution obtained in step 2 after ammonia replenishment is subjected to nanoscale cross-flow filtration with a filtration accuracy of 50nm. After filtration, a clear high-molybdenum solution is obtained for use, and the concentrated solution is returned to step 1 for redissolution. The system that is saturated and redissoluted once is periodically discharged with slag. Step 4, one-time cooling crystallization: The high-molybdenum clear liquid obtained after filtration in step three is subjected to freeze crystallization. The final freeze crystallization temperature is 0 to -3℃. The mother liquor is returned to step one for redissolution to obtain primary crystallized ammonium perrhenate. Step 5, filtration and separation: The primary crystallized ammonium perrhenate obtained in step four was subjected to negative pressure filtration using a 200-mesh filter cloth to obtain a primary crystallized ammonium perrhenate filter cake. Step 6, Secondary Redissolution: The primary crystallized ammonium perrhenate filter cake obtained in step five is subjected to water-saturated secondary redissolution to obtain a secondary ammonium perrhenate solution; Step 7, Second ammonia supplementation to adjust pH: Ammonia water is added to the secondary ammonium perperate solution obtained in step six, and the pH of the secondary ammonium perperate solution is controlled to be greater than 10. The temperature of the secondary ammonium perperate solution during the operation is 70-75℃, so as to obtain the secondary ammonium perperate ammonia replenishment solution. Step 8, Ultrasonic-assisted secondary cooling crystallization: The secondary ammonium perrhenate solution obtained in step seven was subjected to freeze crystallization at a final temperature of 0 to -3°C. Simultaneously, intermittent ultrasonic crystallization was used. The mother liquor was returned to step one for redissolution to obtain secondary crystallized ammonium perrhenate. Step 9, filtration and drying: The secondary crystallized ammonium perrhenate obtained in step eight was filtered through a 50-mesh filter cloth, and the filter cake of the secondary crystallized ammonium perrhenate was dried by microwave to obtain a low-molybdenum ammonium perrhenate product.

2. The method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore as described in claim 1, characterized in that, In step one, the high-molybdenum perrhenate ammonium product is the perrhenate ammonium product obtained during the rhenium recovery process from the rhenium washing liquid of molybdenum concentrate roasting flue gas.

3. The method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore as described in claim 1, characterized in that, In step one, the dissolution temperature is 70–75°C.

4. The method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore as described in claim 1, characterized in that, In step two, the concentration of hydrogen peroxide is 25-30 wt.%, and the volume of hydrogen peroxide added is 0.5-2% of the volume of the high molybdenum solution.

5. The method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore as described in claim 1, characterized in that, In step two, the concentration of ammonia water is 25-38 wt.%, and the volume of ammonia water added is 2-5% of the volume ratio of the high molybdenum solution.

6. The method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore as described in claim 1, characterized in that, In step four, the freezing crystallization process lasts for 12 to 24 hours.

7. The method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore as described in claim 1, characterized in that, In step six, the dissolution temperature for saturated dissolution is 70–75°C.

8. The method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore as described in claim 1, characterized in that, In step seven, the concentration of the ammonia water is 25-38 wt.%, and the volume of ammonia water added is 3-5% of the volume ratio of the secondary perrhenate ammonium solution.

9. The method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore as described in claim 1, characterized in that, In step eight, the frequency of the ultrasound is 40 kHz, and the interval between ultrasound waves is once every 20 to 30 minutes.

10. The method for recovering ammonium perrhenate and removing molybdenum from molybdenum ore as described in claim 1, characterized in that, In step nine, the microwave drying temperature is 120°C and the drying time is 4 hours.

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