Method for preparing high-purity ammonium rhenate from crude rhenate

Abstract

The application relates to a method for preparing high-purity ammonium rhenate from crude rhenate, and the method is specifically performed according to the following steps: S1, preparing a crude rhenate solution; S2, preparing a calcium hydroxide suspension; S3, separating anion impurities in the crude rhenate solution by using the calcium hydroxide suspension, and obtaining a rhenate filtrate; S4, separating cation impurities in the rhenate filtrate by using a cation resin adsorption, and obtaining a rhenate solution; S5, treating the rhenate solution by using a two-chamber bipolar membrane membrane stack electrodialysis system, and obtaining a perrhenic acid solution; and S6, preparing ammonium rhenate from the perrhenic acid solution and ammonia water. The method for preparing high-purity ammonium rhenate from crude rhenate has a short technological process, is easy to operate, and has the advantages that the impurities in the crude rhenate form an open circuit, the recovery rate of the process is higher than 99%, the purity of the obtained ammonium rhenate is higher than 99.995%, the quality of the ammonium rhenate product is stable, no waste water and waste gas are generated, the environmental protection advantage is obvious, evaporation and concentration are not needed, and the energy consumption is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metallurgy, in particular to a method for preparing high-purity ammonium perrhenate from crude perrhenate. BACKGROUND

[0002] The mass fraction of rhenium in the earth's crust is only 1x10 -9 , which belongs to a rare metal and has no independent smeltable rhenium mineral. Due to the excellent properties of rhenium, such as high melting point, high hardness, anti-creep property, corrosion resistance, and good plasticity, rhenium occupies an important position in the fields of chemical industry, metallurgy, aerospace, and cutting-edge science of national defense. The main raw material for preparing metallic rhenium in industry is ammonium perrhenate (NH4ReO4), which is a white hexagonal system cubic bipyramid crystal. The purity of ammonium perrhenate plays a decisive role in the purity of rhenium products, and the purity of metallic rhenium affects its application performance. Poor purity will damage the application of rhenium at high temperature and high vacuum. Therefore, it is crucial to purify ammonium perrhenate and prepare high-purity ammonium perrhenate. Currently, the main methods for purifying ammonium perrhenate include precipitation, activated carbon adsorption, extraction, ion exchange, etc. However, the above methods have some defects to varying degrees. For example, a large amount of alkaline wastewater is generated during the washing process, which is heavy in wastewater treatment and is not suitable for industrial-scale production. For another example, the addition of oxidizing agents such as hydrogen peroxide only has a removal effect on a few metal impurities such as Fe and Cu, and has a weak removal effect on other metal impurities.

[0003] Currently, the main purification methods are oxidation-filtration and filtration-recrystallization. After the impurities enter the mother liquor, they will eventually be enriched in the ammonium perrhenate product. With the increase in the number of crystallizations, the purity of the ammonium perrhenate product gradually decreases, and the impurities do not form an open circuit. SUMMARY

[0004] To solve the above technical problems, the present application provides a method for preparing high-purity ammonium perrhenate from crude perrhenate. The process flow is short and easy to operate. The impurities in the crude perrhenate form an open circuit, and the recovery rate of the process is higher than 99%. The purity of the obtained ammonium perrhenate is above 99.995%, and the quality of the ammonium perrhenate product is stable. No wastewater and waste gas are generated, which has obvious environmental protection advantages. Evaporation concentration is not required, and the energy consumption is low.

[0005] The technical solution adopted by the present application to solve the technical problems is as follows: a method for preparing high-purity ammonium perrhenate from crude perrhenate, which is specifically performed according to the following steps:

[0006] S1, preparing a crude perrhenate solution, wherein the crude perrhenate is crude ammonium perrhenate or crude potassium perrhenate, and the mass percentage content of rhenium in the crude perrhenate is not less than 62.45%; the crude perrhenate solution is an aqueous solution of the crude perrhenate, and the mass-volume concentration of rhenium in the crude perrhenate solution is 30-60 g / L;

[0007] S2, preparing a calcium hydroxide suspension, wherein the calcium hydroxide suspension is prepared by mixing calcium oxide and deionized water in a mass ratio of 1:1;

[0008] S3, adding the calcium hydroxide suspension of step S2 to the crude rhenate solution of step S1, adjusting the pH to 10-12, and stirring for 1-5 h; centrifuging and filtering to obtain a rhenate filtrate;

[0009] S4, adsorbing the rhenate filtrate obtained in step S3 using a cation resin, and flowing out a rhenate solution;

[0010] S5, adding the rhenate solution treated in step S4 to a two-chamber bipolar membrane stack electrodialysis system; under the action of a direct current electric field force, water in the bipolar membrane dissociates to form H + , HO - , which migrate out from the anode and cathode sides of the bipolar membrane, respectively; the rhenate solution in the salt chamber is electrolyzed by the bipolar membrane, NH4 + or K + migrates from the cation exchange membrane into the base chamber, thereby forming NH4OH or KOH with OH - migrating out from the cathode side of the bipolar membrane, and the salt chamber loses NH4 + or K + to obtain H + , thereby gradually reducing the pH, controlling the pH of the salt chamber to be 0-1, and discharging a high rhenium acid solution;

[0011] S6, under stirring, adding ammonia water to the high rhenium acid solution obtained in step S5, and maintaining the reaction temperature at -2-2°C; after the reaction is completed, centrifuging; washing the solid phase, and drying to obtain high-purity ammonium rhenate.

[0012] Further, in step S3, the mass ratio of the crude rhenate solution to the calcium hydroxide suspension is (10-1000):1.

[0013] Further, in step S3, the anion impurity content of the prepared rhenate filtrate is not higher than 30 mg / L.

[0014] Further, in step S3, the solid phase after centrifugation and filtration is washed with water, and the washing water is returned to the crude rhenate solution of step S1.

[0015] Further, in step S4, the cation resin is a chelating resin of MTS9300 brand; and the adsorption linear speed is 1-3 m / h.

[0016] Further, in step S4, the cation impurity content of the prepared rhenate solution is not higher than 0.3 mg / L.

[0017] Further, in step S5, the mass-volume concentration of NH4OH or KOH in the alkali chamber is controlled at 40-150 g / L.

[0018] Further, in step S6, the stirring frequency is 300-400 r / min.

[0019] Further, in step S6, the mass percentage concentration of the ammonia water is 25-28%.

[0020] Further, in step S6, the amount of the ammonia water added is 1.02-1.1 times the amount of the rhenium in the high-rhenium acid solution. + Further, in step S6, the molar ratio of the rhenium in the high-rhenium acid solution to the ammonia water is (1.02-1.1):1.

[0021] The method for preparing high-purity ammonium rhenate from a crude rhenate salt according to the present application has the following advantages: the rhenium content in the raw material used is as low as 62.45%, and impurities are removed through precipitation, ion exchange, and bipolar membrane electrodialysis, and high-purity ammonium rhenate is obtained through ammonia neutralization and cooling crystallization; compared with the prior art, the method is suitable for crude rhenate salt raw materials with high impurity content and has strong versatility; the required auxiliary materials are few, and the auxiliary materials are recycled in the process, without generating waste water or waste gas, and the environmental protection advantage is obvious; the purity of the obtained ammonium rhenate is above 99.995%, and the ammonium rhenate product quality is stable, and the rhenium metal recovery rate is above 99%; the process flow is short, and the rhenium concentration in the ammonium rhenate solution does not need to be increased through concentration, the energy consumption is low, and the process is highly controlled. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure is a process flow chart of the method for preparing high-purity ammonium rhenate from a crude rhenate salt according to the present application. DETAILED DESCRIPTION

[0023] In order to deepen the understanding of the present application, the present application will be further described in detail below in combination with the drawings and examples, which are only used to explain the present application and do not limit the protection scope of the present application.

[0024] The method for preparing high-purity ammonium rhenate from a crude rhenate salt according to the present application includes the following contents:

[0025] I. Source of the crude rhenate salt raw material

[0026] The crude rhenate salt solution referred to in the present method is various crude ammonium rhenate, crude potassium rhenate solid or solution, etc., and the rhenium content in the crude rhenate salt is >62.45%.

[0027] II. Purification of the crude rhenate salt solution

[0028] (I) Separation of rhenium and anion impurities

[0029] In the heatable reaction kettle, add crude ammonium rhenate or crude potassium rhenate solid and water to heat and dissolve, control the temperature at 70-90°C, or directly use crude rhenate solution as raw material, control the rhenium concentration at 30-60g / L at the end of dissolution, at the same time, use calcium oxide (food grade) and deionized water to prepare calcium hydroxide suspension according to liquid-solid ratio 1:1;

[0030] According to the mass ratio of crude rhenate solution to calcium hydroxide suspension (10-1000):1, add calcium hydroxide suspension to the crude rhenate solution, adjust the pH of the above-mentioned crude rhenate solution to 10-12, stir and react for 1-5 hours, realize deep separation of rhenium and anion impurities through centrifugal filtration, realize that the content of P, As, Si, W, Mo, V, CO3 2- , SO4 2- , etc. is lower than 30mg / L, collect multiple batches of solid phase obtained by centrifugation and uniformly heat and pulp water washing, and return the washing water to the crude rhenate solution.

[0031] (II) Separation of rhenium and cation impurities

[0032] The above-mentioned rhenate filtrate is adsorbed by MTS9300 chelating resin, the adsorption linear speed is 1-3m / h, the content of Cu, Fe, Ca, Mg, Co, Ni, Cr, etc. in the rhenate solution flowing out after adsorption is lower than 0.3mg / L, and the solution is used for preparing high-purity perrhenic acid, and after the resin adsorption penetration, the steps of washing, regeneration, etc. are carried out.

[0033] III. Preparation of high-purity rhenic acid solution

[0034] The above-mentioned purified rhenate solution passes through a two-chamber bipolar membrane membrane stack electrodialysis system, under the action of direct current electric field force, water in the bipolar membrane is dissociated to form H + , HO - , which migrates out from the positive membrane side and the negative membrane side of the bipolar membrane, respectively; the rhenate solution in the salt chamber passes through the bipolar membrane electrolysis, NH4 + or K + migrates into the alkali chamber from the cation exchange membrane to form NH4OH or KOH with OH - migrated out from the negative membrane side of the bipolar membrane, the salt chamber loses NH4 + or K + to obtain H + , so that the pH gradually decreases, the high rhenic acid solution is obtained by discharging when the pH of the salt chamber is 0-1, the concentration of NH4OH or KOH in the alkali chamber is controlled at 40-150g / L according to the concentration of Re in the rhenate solution supplemented in the salt chamber, and the hydroxide returns to the raw material leaching section for raw material leaching, realizing the recycling of NH4 + or K + in the process.

[0035] The membrane stack of the two-chamber bipolar membrane electrodialysis system is a two-chamber bipolar membrane stack, consisting of multiple bipolar membrane and cation membrane pairs. From cathode to anode, the stacks are arranged in order: electrode plates, flow guide grids, bipolar membranes, flow guide grids, and cation membranes. Multiple repeating units of membrane pairs consisting of bipolar membranes, flow guide grids, and cation exchange membranes, bipolar membranes, flow guide grids, and electrode plates are also included. The electrode plates are made of titanium-plated tantalum-iridium, the flow guide grids are made of PTFE, and both the bipolar membranes and cation exchange membranes are alkali-resistant homogeneous membranes. The anionic membrane of the bipolar membrane, the flow guide grid, and the anode plate form the anode chamber, while the anionic membrane of the bipolar membrane, the flow guide grid, and the cation exchange resin form the alkali chamber. The salt chamber is formed between the cation exchange membrane, the flow guide grid, and the bipolar membrane's cation. The alkali chamber and the salt chamber alternate to form a repeating unit, and the cation membrane of the bipolar membrane, the flow guide grid, and the cathode plate form the cathode chamber. The two-chamber bipolar membrane stack electrodialysis system also includes an AC-to-DC converter, a cathode solution circulation tank, a salt solution circulation tank, an alkali solution circulation tank, an cathode solution circulation pump, a salt solution circulation pump, and an alkali solution circulation pump. Required auxiliary materials include a 2% to 4% by weight NaOH solution as the cathode liquid for the cathode chamber, a salt-free solution as the alkali chamber supplemental solution, and a purified rhenate solution as the salt chamber supplemental solution.

[0036] 4. Crystallization of high-purity rhenic acid products

[0037] The high-purity rhenic acid solution is transferred to a double-layer crystallization reactor. The double-layer reactor is made of heat-resistant glass, jacketed titanium alloy reactor or glass-lined reactor, which will not introduce contamination to the reaction. Stirring is started, and the stirring frequency is set to 300-400 r / min. High-purity ammonia water (Wt: 25%-28%, GR grade) is added to the reactor. The amount of high-purity ammonia water added is NH4 + The molar ratio of rhenium to high-purity rhenic acid is 1.02-1.1:1. The double-layer reactor is continuously cooled at a refrigerant temperature of -50°C, and the solution in the reactor is cooled to -2°C to 2°C. The solid-liquid mixture in the double-layer reactor is discharged into a centrifuge. After the mother liquor is separated by high-speed centrifugation, the ammonium rhenate product is washed 2-5 times with ultrapure water at 1-2°C. After centrifugation, the moisture content of the ammonium rhenate is ≤0.5%. A two-stage air filter is installed at the air inlet of a constant temperature hot air dryer, and the temperature is set at 60-80°C for 8-12 hours to obtain ultrafine high-purity ammonium rhenate.

[0038] Example 1

[0039] Into the reactor, add crude ammonium rhenate and deionized water, and heat to 80°C. The rhenium content of the crude ammonium rhenate is 62.5%, and the rhenium concentration of the crude ammonium rhenate solution is 45.3 g / L. A calcium oxide (food grade) suspension is prepared by mixing calcium oxide and deionized water at a liquid-solid ratio of 1:1. The suspension is added to the crude ammonium rhenate solution at a mass ratio of 18:1, and the pH is adjusted to 12. The mixture is stirred for 5 hours, and then centrifuged and filtered. The filtered ammonium rhenate solution is adsorbed by a MTS9300 chelating resin at a linear velocity of 1 m / h. The impurities Cu, Fe, Ca, Mg, Co, Ni, and Cr in the ammonium rhenate solution after adsorption are less than 0.3 mg / L. The purified ammonium rhenate solution is subjected to an electrodialysis system with a two-chamber bipolar membrane membrane stack, and the pH in the salt chamber is controlled at 0-1 to obtain a perrhenic acid solution. The perrhenic acid solution is transferred to a double-layer crystallization reactor, and the stirring frequency is set to 300 r / min. High-purity ammonia water (wt: 25%-28%, GR grade) is added to the reactor at a molar ratio of 1.05:1 with respect to the rhenium in the perrhenic acid. The solution in the reactor is cooled to 1°C, and the solid-liquid mixture is separated by high-speed centrifugation. The ammonium rhenate product is washed twice with ultrapure water at 1-2°C, and dried in a constant-temperature hot air drying machine at 60°C for 12 hours to obtain high-purity ammonium rhenate. +

[0040] After inspection, the purity of the ammonium rhenate is greater than 99.995%, and the rhenium recovery rate of the process is 99.2%.

[0041] Example Two

[0042] Into the reactor, add crude potassium rhenate and deionized water, and heat to 70°C. The rhenium content of the crude ammonium rhenate is 62.7%, and the rhenium concentration of the crude potassium rhenate solution is 48.1 g / L. A calcium oxide (food grade) suspension is prepared by mixing calcium oxide and deionized water at a liquid-solid ratio of 1:1. The suspension is added to the crude potassium rhenate solution at a mass ratio of 30:1, and the pH is adjusted to 10. The mixture is stirred for 3 hours, and then centrifuged and filtered. The filtered potassium rhenate solution is adsorbed by a MTS9300 chelating resin at a linear velocity of 2 m / h. The impurities Cu, Fe, Ca, Mg, Co, Ni, and Cr in the potassium rhenate solution after adsorption are less than 0.3 mg / L. The purified potassium rhenate solution is subjected to an electrodialysis system with a two-chamber bipolar membrane membrane stack, and the pH in the salt chamber is controlled at 0-1 to obtain a perrhenic acid solution. The perrhenic acid solution is transferred to a double-layer crystallization reactor, and the stirring frequency is set to 350 r / min. High-purity ammonia water (wt: 25%-28%, GR grade) is added to the reactor at a molar ratio of 1.05:1 with respect to the rhenium in the perrhenic acid. The solution in the reactor is cooled to 1°C, and the solid-liquid mixture is separated by high-speed centrifugation. The potassium rhenate product is washed twice with ultrapure water at 1-2°C, and dried in a constant-temperature hot air drying machine at 60°C for 12 hours to obtain high-purity potassium rhenate. + ​The solution in the pot was cooled to 0°C, and after cooling, the solid-liquid mixture was separated by high-speed centrifugation, the ammonium perrhenate product was washed with 1-2°C ultrapure water for 3 times, and was dried in a constant-temperature hot air drying machine at 80°C for 8 hours to obtain high-purity ammonium perrhenate.

[0043] The purity of the ammonium perrhenate was greater than 99.995%, and the recovery rate of rhenium in the process was 99.1%.

[0044] Example Three

[0045] The crude ammonium perrhenate solution was added into a reaction kettle and heated to 90°C. The rhenium content of the crude ammonium perrhenate was 63.5%, and the rhenium concentration was 49.3 g / L. Calcium oxide (food grade) and deionized water were mixed to form a calcium hydroxide suspension according to a liquid-solid ratio of 1:1. The calcium hydroxide suspension was added to the crude ammonium perrhenate solution according to a mass ratio of 50:1, and the pH was adjusted to 11. The mixture was stirred for 1 hour, and then centrifuged and filtered. The filtered rhenium salt solution was adsorbed by a MTS9300 chelating resin with a linear velocity of 1 m / h. The impurities such as Cu, Fe, Ca, Mg, Co, Ni and Cr in the rhenium salt solution flowing out after adsorption were less than 0.3 mg / L. The purified rhenium salt solution was subjected to a two-chamber bipolar membrane stack electrodialysis system, and the pH in the salt chamber was controlled at 0-1 to obtain a high-purity perrhenic acid solution. The perrhenic acid solution was transferred into a double-layer crystallization reaction kettle, and the stirring frequency was set to 400 r / min. High-purity ammonia water (wt: 25%-28%, GR grade) was added into the reaction kettle. The amount of the ammonia water was determined according to the NH4 + The solution in the pot was cooled to 0°C, and after cooling, the solid-liquid mixture was separated by high-speed centrifugation, the ammonium perrhenate product was washed with 1-2°C ultrapure water for 3 times, and was dried in a constant-temperature hot air drying machine at 80°C for 8 hours to obtain high-purity ammonium perrhenate.

[0046] The purity of the ammonium perrhenate was greater than 99.995%, and the recovery rate of rhenium in the process was 99.1%.

[0047] The above method for preparing high-purity ammonium perrhenate from crude rhenium salt uses a raw material with a rhenium content as low as 62.45%. The method adopts processes such as precipitation, ion exchange impurity removal and bipolar membrane electrodialysis to remove impurities, and obtains high-purity ammonium perrhenate through ammonia neutralization and cooling crystallization. Compared with the prior art, the method has the advantages of forming an open circuit for impurities, being suitable for crude rhenium salt raw materials with high impurity content and having strong versatility. The method requires fewer types of auxiliary materials, and the auxiliary materials are recycled in the process without generating wastewater or waste gas, which has obvious environmental protection advantages. The purity of the obtained ammonium perrhenate is greater than 99.995%, and the ammonium perrhenate product has stable quality and a rhenium metal recovery rate of greater than 99%. The process flow is short, and the rhenium concentration in the ammonium perrhenate solution does not need to be increased by concentration, which reduces energy consumption and improves the controllability of the process.

[0048] The above embodiments should not be taken as limiting the application in any way, and any technical solutions obtained by equivalent substitution or equivalent conversion shall fall within the protection scope of the application.

Claims

1. A method for preparing high purity ammonium rhenate from a crude rhenate, characterized by: The method is carried out according to the following steps: S1, preparing a crude rhenate solution, wherein the crude rhenate is crude ammonium rhenate or crude potassium rhenate, the mass percentage content of rhenium in the crude rhenate is not less than 62.45%; the crude rhenate solution is an aqueous solution of the crude rhenate, and the mass-volume concentration of rhenium in the crude rhenate solution is 30-60 g / L; S2, preparing a calcium hydroxide suspension, wherein the calcium hydroxide suspension is prepared by mixing calcium oxide and deionized water in a mass ratio of 1:1; S3, adding the calcium hydroxide suspension of step S2 to the crude rhenate solution of step S1, adjusting the pH to 10-12, and stirring and reacting for 1-5 h; centrifuging and filtering to obtain a rhenate filtrate; S4, adsorbing the rhenate filtrate obtained in step S3 by using a cation resin, and flowing out a rhenate solution after adsorption; S5, the rhenium solution treated by step S4 is added to a two-chamber bipolar membrane membrane stack electrodialysis system; under the action of a direct current electric field force, water in the bipolar membrane is dissociated to form H + - , which migrates out from the positive membrane side and the negative membrane side of the bipolar membrane, respectively; the rhenium solution in the salt chamber is subjected to bipolar membrane electrolysis, NH4 + or K + migrates from the cation exchange membrane into the base chamber, thereby forming NH4OH or KOH with OH - migrated out from the negative membrane side of the bipolar membrane, and the salt chamber loses NH4 + or K + to obtain H + , so that the pH gradually decreases, the pH of the salt chamber is controlled at 0-1, and a high perrhenic acid solution is discharged;​ S6, under the condition of stirring, adding ammonia water to the high rhenium acid solution obtained in step S5, and keeping the reaction temperature at-2-2 ℃; after the reaction is completed, centrifuging; washing the solid phase and drying to obtain high-purity ammonium rhenate.

2. The method for preparing high purity ammonium rhenate from crude rhenate according to claim 1, characterized in that: In step S3, the mass ratio of the crude rhenate solution to the calcium hydroxide suspension is (10-1000):

1.

3. The method of claim 1, wherein the method is characterized by: In step S3, the anion impurity content of the prepared rhenate filtrate is not higher than 30 mg / L.

4. The method for preparing high purity ammonium rhenate from a crude rhenate salt according to any one of claims 1 to 3, characterized in that: In step S3, the solid phase after centrifugal filtration is washed with water, and the washing water is returned to the crude rhenate solution of step S1.

5. The method of claim 1, wherein the method is characterized by: In step S4, the cation resin is a chelating resin of MTS9300 brand; the adsorption linear speed is 1-3 m / h.

6. The method for preparing high purity ammonium rhenate according to claim 1 or 5, characterized in that: In step S4, the cation impurity content of the prepared rhenate solution is not higher than 0.3 mg / L.

7. The method of claim 1, wherein the method is characterized by: In step S5, the mass-volume concentration of NH4OH or KOH in the alkali chamber is controlled at 40-150 g / L.

8. The method of claim 1, wherein the method is characterized by: In step S6, the stirring frequency is 300-400 r / min.

9. The method of claim 1, wherein the method is characterized by: In step S6, the mass percentage concentration of ammonia water is 25-28%.

10. The method for preparing high purity ammonium rhenate according to claim 8 or 9, characterized in that: In step S6, the amount of ammonia water added is such that the molar ratio of NH4 + to the rhenium in the perrhenic acid solution is (1.02-1.1): 1.

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