Method for preparing high-purity ammonium rhenate from crude rhenate

Abstract

The invention relates to a method for preparing high-purity ammonium rhenate from crude rhenate. The method specifically comprises the following steps: S1, preparing a crude rhenate solution; s2, preparing a calcium hydroxide suspension; s3, anion impurities in the crude rhenate solution are separated through the calcium hydroxide suspension, and rhenate filtrate is obtained; s4, cation impurities in the rhenate filtrate are adsorbed and separated through cation resin, and a rhenate solution is obtained; s5, treating through a two-chamber bipolar membrane stack electrodialysis system to obtain a perrhenic acid solution; and S6, ammonium rhenate is prepared from ammonium hydroxide in a perrhenic acid solution. According to the method for preparing the high-purity ammonium rhenate from the crude rhenate, the technological process is short and easy to operate, impurities in the crude rhenate form an open circuit, and the flow recovery rate is higher than 99%; the purity of the obtained ammonium rhenate is 99.995% or above, the ammonium rhenate product is stable in quality, waste water and waste gas are not generated, and the method has the advantages of being obvious in environmental protection advantage, free of evaporation and concentration and low in energy consumption.

Description

Technical Field

[0001] The invention relates to the field of metallurgy, and in particular to a method for preparing high-purity ammonium rhenate from crude rhenate. Background Art

[0002] The mass fraction of rhenium in the earth's crust is only 1×10 -9 , belongs to the rare metal, and there is no independently smeltable rhenium mineral. Due to its excellent properties such as high melting point, high hardness, creep resistance, corrosion resistance and good plasticity, rhenium occupies an important position in the cutting-edge scientific fields of chemical industry, metallurgy, aerospace and national defense. The raw materials for the preparation of metallic rhenium in industry are mainly ammonium rhenate (NH 4 R 4 ), which is a white hexagonal cubic bipyramidal crystal. The purity of ammonium rhenate plays a decisive role in the purity of rhenium products, while the purity of metallic rhenium affects its application performance. Poor purity will damage the application of rhenium in high temperature and high vacuum. Therefore, it is crucial to purify ammonium rhenate and prepare high-purity ammonium rhenate. At present, the main methods for purifying ammonium rhenate include precipitation method, activated carbon adsorption method, extraction method, ion exchange method, etc. However, the above methods all have some defects to varying degrees. For example, a large amount of alkaline wastewater will be generated during the washing process, the wastewater post-treatment burden is heavy, and it is not suitable for industrial-scale production; for another example, the addition of oxidants such as hydrogen peroxide only has a removal effect on a few metal impurities such as Fe and Cu, and the removal effect on other metal impurities is relatively weak.

[0003] At present, 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 rhenate product. As the number of crystallizations increases, the purity of the ammonium rhenate product decreases step by step, and the impurities do not form an open circuit. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing high-purity ammonium rhenate from crude rhenate. The process flow is short and easy to operate. Impurities in the crude rhenate form an open circuit, and the process recovery rate is higher than 99%. The purity of the obtained ammonium rhenate is higher than 99.995%, and the quality of the ammonium rhenate product is stable, no waste water or waste gas is generated, and the environmental protection advantage is obvious. No evaporation and concentration are required, and the energy consumption is low.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing high-purity ammonium rhenate from crude rhenate, which is specifically carried out according to the following steps:

[0006] S1. preparing a crude rhenate solution, wherein the crude rhenate is crude ammonium rhenate or crude potassium rhenate, and 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;

[0007] S2. Prepare 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, stirring and reacting for 1-5 hours; centrifuging and filtering to obtain a rhenate filtrate;

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

[0010] S5, adding the rhenate solution treated in step S4 to a two-chamber bipolar membrane stack electrodialysis system; under the action of the DC electric field force, the water in the bipolar membrane dissociates to form H + , HO - , respectively migrate out from the positive membrane side and the negative membrane side of the bipolar membrane; the rhenate solution in the salt chamber undergoes bipolar membrane electrolysis, NH 4 + or K + The OH migrates from the cation exchange membrane into the base chamber, thereby interacting with the OH migrated from the anion side of the bipolar membrane. - Formation of NH 4 OH or KOH, the salt chamber loses NH 4 + or K + Get H + , so that the pH gradually decreases, and the pH of the salt chamber is controlled at 0-1 to obtain a perrhenic acid solution;

[0011] S6. Under stirring conditions, add aqueous ammonia to the perrhenic acid solution obtained in step S5, and maintain the reaction temperature at -2 to 2°C; after the reaction is completed, centrifuge; wash and dry the solid phase to obtain high-purity ammonium rhenate.

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

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

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

[0015] Furthermore, in step S4, the cationic resin is a chelating resin of the MTS9300 brand; and the adsorption linear velocity is 1 to 3 m / h.

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

[0017] Further, in step S5, in the alkali chamber, NH 4 The mass volume concentration of OH or KOH is controlled at 40-150 g / L.

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

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

[0020] Further, in step S6, the amount of ammonia added is NH 4 + The molar ratio of rhenium to perrhenic acid solution is (1.02~1.1):1.

[0021] The invention has the following advantages: the method for preparing high-purity ammonium rhenate from crude rhenate has the following advantages: the rhenium content in the raw material used is as low as 62.45%, and the impurities are removed by precipitation, ion exchange impurity removal, bipolar membrane electrodialysis and other processes, and the high-purity ammonium rhenate is obtained by ammonia neutralization and cooling crystallization; compared with the prior art, the impurities form an open circuit, which is suitable for crude rhenate raw materials with high impurity content and has strong versatility; the required auxiliary materials are of fewer varieties, and the auxiliary materials are recycled in the process, and no waste water or waste gas is generated, which has obvious environmental protection advantages; the purity of the obtained ammonium rhenate is above 99.995%, and the quality of the ammonium rhenate product is stable, and the rhenium metal recovery rate is higher than 99%; the process flow is short, and there is no need to increase the rhenium concentration in the ammonium rhenate solution by concentration, so the energy consumption is low and the process is highly controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a process flow chart of a method for preparing high-purity ammonium rhenate from crude rhenate. DETAILED DESCRIPTION

[0023] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments are only used to explain the present invention and do not limit the protection scope of the present invention.

[0024] A method for preparing high-purity ammonium rhenate from crude rhenate of the present invention comprises the following contents:

[0025] 1. Source of crude rhenate raw materials

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

[0027] 2. Purification of crude rhenate solution

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

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

[0030] According to the mass ratio of crude rhenate solution to calcium hydroxide suspension (10-1000):1, the calcium hydroxide suspension is added to the crude rhenate solution, the pH of the crude rhenate solution is adjusted to 10-12, the reaction is stirred for 1-5 hours, and the deep separation of rhenium and anionic impurities is achieved by centrifugal filtration to achieve the separation of P, As, Si, W, Mo, V, CO 3 2- 、SO 4 2- When the impurity content is less than 30 mg / L, the solid phase obtained by centrifugation is collected in batches and then uniformly heated, pulped and washed with water, and the washing water is returned to the crude rhenate solution.

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

[0032] The above-mentioned rhenate filtrate is adsorbed by MTS9300 brand chelating resin with an adsorption linear speed of 1 to 3 m / h. The impurity content of Cu, Fe, Ca, Mg, Co, Ni, Cr, etc. in the rhenate solution flowing out after adsorption is less than 0.3 mg / L. The solution is used to prepare high-purity perrhenic acid. After the resin adsorption penetrates, it enters the washing, regeneration and other steps.

[0033] 3. Preparation of high purity rhenic acid solution

[0034] The purified rhenate solution is passed through a two-chamber bipolar membrane stack electrodialysis system. Under the action of the DC electric field, the water in the bipolar membrane dissociates to form H + , HO - , respectively migrate out from the positive membrane side and the negative membrane side of the bipolar membrane; the rhenate solution in the salt chamber undergoes bipolar membrane electrolysis, NH 4 + or K + The OH migrates from the cation exchange membrane into the base compartment and combines with the OH migrated from the anion side of the bipolar membrane. - Formation of NH 4 OH or KOH, the salt chamber loses NH 4 + or K + Get H + The pH value is gradually reduced, and the pH value of the salt chamber is controlled at 0-1 to obtain a perrhenic acid solution. The NH 4The concentration of OH or KOH is controlled at 40-150 g / L, and the hydroxide is returned to the raw material leaching section for raw material leaching, realizing the NH 4 + or K + recycling.

[0035] Among them, the membrane stack of the two-chamber bipolar membrane stack electrodialysis system is a two-chamber bipolar membrane stack, which is composed of multiple membrane pairs of bipolar membranes and cation membranes. From the direction from cathode to anode, they are electrode plates, guide grids, bipolar membranes, guide grids, and cation membranes; multiple membrane pair repeating units composed of bipolar membranes, guide grids, and cation exchange membranes, bipolar membranes, guide grids, and electrode plates. Among them, the electrode plates are made of titanium-plated tantalum-iridium material, the guide grids are made of PTFE material, and the bipolar membranes and cation exchange membranes are both alkali-resistant homogeneous membranes. The anion membrane of the bipolar membrane, the guide grid, and the anode plate constitute the anode chamber, the anion membrane of the bipolar membrane, the guide grid, and the cation exchange resin constitute the alkali chamber, the cation exchange membrane, the guide grid, and the cation membrane of the bipolar membrane are between the salt chamber, the alkali chamber and the salt chamber alternately form repeating units, and the cation membrane of the bipolar membrane, the guide grid, and the cathode plate constitute the cathode chamber. The two-chamber bipolar membrane stack electrodialysis system also includes an AC to DC conversion power supply, a polar chamber solution circulation tank, a salt chamber solution circulation tank, an alkali chamber solution circulation tank, a polar chamber solution circulation delivery pump, a salt chamber solution circulation delivery pump, and an alkali chamber solution circulation delivery pump. Required auxiliary materials: 2% to 4% NaOH solution as the polar chamber polar liquid, salt-free water as the alkali chamber supplementary liquid, and purified rhenate solution as the salt chamber supplementary liquid.

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

[0037] The high-purity rhenic acid solution is transferred into a double-layer crystallization reactor. The double-layer reactor is made of heat-resistant glass, jacketed titanium alloy reactor or glass-lined reactor, etc., which will not introduce pollution to the reaction. Stirring is started, and the stirring frequency is set to 300-400r / min. High-purity ammonia water (Wt: 25%-28%, GR grade) is added to the reactor. The amount of high-purity ammonia water added is NH 4 + The molar ratio of rhenium to high-purity rhenic acid is (1.02-1.1):1; the refrigerant temperature is set at -50°C to continuously cool the double-layer reactor, the solution in the reactor is cooled to -2°C-2°C, the solid-liquid mixture in the double-layer reactor is discharged to a centrifuge, the mother liquor is separated by high-speed centrifugation, and the ammonium rhenate product is washed 2-5 times with 1-2°C ultrapure water, and the moisture content of the ammonium rhenate after centrifugation is ≤0.5%. A two-stage air filter is installed at the air inlet of the constant temperature hot air dryer, and the temperature is set at 60-80°C for drying for 8-12 hours to obtain ultrafine high-purity ammonium rhenate.

[0038] Embodiment 1

[0039] Add crude ammonium rhenate and deionized water into the reactor and heat to 80°C. The rhenium content in the crude ammonium rhenate is 62.5%, and the rhenium concentration of the crude ammonium rhenate solution is 45.3 g / L. Calcium oxide (food grade) and deionized water are modulated at a liquid-solid ratio of 1:1 to form a calcium hydroxide suspension. According to the mass ratio of the crude rhenate solution to the calcium hydroxide suspension of 18:1, the calcium hydroxide suspension is added to the crude rhenate solution, the pH is adjusted to 12, the reaction is stirred for 5 hours, and the filtered rhenate solution is passed through MTS9300 The invention relates to a method for adsorbing a chelating resin of a certain grade, with an adsorption linear speed of 1 m / h. The impurity content of Cu, Fe, Ca, Mg, Co, Ni, Cr and the like in the rhenate solution discharged after adsorption is less than 0.3 mg / L. The rhenate solution after adsorption and purification passes through a two-chamber bipolar membrane stack electrodialysis system, and the pH value of the salt chamber is controlled at 0 to 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% to 28%, GR grade) is added to the reactor, and the amount of the added ammonia water is NH4OH. 4 + The molar ratio of rhenium to perrhenic acid is 1.05:1; the solution in the pot is cooled to 1°C, the solid-liquid mixture is separated by high-speed centrifugation after cooling, the ammonium rhenate product is washed twice with 1-2°C ultrapure water, and dried in a constant temperature hot air dryer at 60°C for 12 hours to obtain high-purity ammonium rhenate.

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

[0041] Embodiment 2

[0042] Crude potassium rhenate and deionized water were added to the reactor and heated to 70°C. The rhenium content in the crude ammonium rhenate was 62.7%, and the rhenium concentration of the crude potassium rhenate solution was 48.1 g / L. Calcium oxide (food grade) and deionized water were modulated at a liquid-solid ratio of 1:1 to form a calcium hydroxide suspension. The calcium hydroxide suspension was added to the crude rhenate solution at a mass ratio of 30:1 between the crude rhenate solution and the calcium hydroxide suspension. The pH was adjusted to 10, the reaction was stirred for 3 hours, and the filtered rhenate solution was passed through MTS9300. The invention relates to a method for adsorbing a chelating resin of a certain grade, with an adsorption linear speed of 2 m / h. The impurities content of Cu, Fe, Ca, Mg, Co, Ni, Cr, etc. in the rhenate solution discharged after adsorption is less than 0.3 mg / L. The rhenate solution after adsorption and purification passes through a two-chamber bipolar membrane stack electrodialysis system, and the pH value of 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, and the amount of the added ammonia water is NH4OH. 4 +The molar ratio of rhenium to perrhenic acid is 1.07:1; the solution in the pot is cooled to 0°C, the solid-liquid mixture is separated by high-speed centrifugation after cooling, the ammonium rhenate product is washed 3 times with 1-2°C ultrapure water, and dried in a constant temperature hot air dryer at 80°C for 8h to obtain high-purity ammonium rhenate.

[0043] The purity of ammonium rhenate was tested to be >99.995%, and the rhenium recovery rate of the process was 99.1%.

[0044] Embodiment 3

[0045] Add crude ammonium rhenate solution into the reactor and heat to 90°C. The crude ammonium rhenate has a rhenium content of 63.5% and a rhenium concentration of 49.3 g / L. Calcium oxide (food grade) and deionized water are modulated at a liquid-solid ratio of 1:1 to form a calcium hydroxide suspension. The calcium hydroxide suspension is added to the crude rhenate solution at a mass ratio of 50:1 between the crude rhenate solution and the calcium hydroxide suspension. The pH is adjusted to 11. The reaction is stirred for 1 hour and centrifuged. The filtered rhenate solution is passed through a chelating resin of MTS9300. Adsorption, adsorption linear speed 1m / h, the impurity content of Cu, Fe, Ca, Mg, Co, Ni, Cr and the like in the rhenate solution discharged after adsorption is less than 0.3mg / L, the rhenate solution after adsorption purification passes through a two-chamber bipolar membrane stack electrodialysis system, the pH of 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, the stirring frequency is set at 400r / min, high-purity ammonia water (Wt: 25%-28%, GR grade) is added to the reactor, the amount of which is NH 4 + The molar ratio of rhenium to perrhenic acid is 1.1:1; the solution in the pot is cooled to -2°C, the solid-liquid mixture is separated by high-speed centrifugation after cooling, the ammonium rhenate product is washed 5 times with 1-2°C ultrapure water, and dried in a constant temperature hot air dryer at 70°C for 10 hours to obtain high-purity ammonium rhenate.

[0046] The purity of ammonium rhenate was tested to be >99.995%, and the recovery rate of rhenium in the process was 99.3%.

[0047] The method for preparing high-purity ammonium rhenate from crude rhenate in the above-mentioned embodiment has a rhenium content as low as 62.45% in the raw material used, and adopts precipitation, ion exchange impurity removal, bipolar membrane electrodialysis and other processes to remove impurities, and obtains high-purity ammonium rhenate through ammonia neutralization and cooling crystallization; compared with the prior art, impurities form an open circuit, which is suitable for crude rhenate raw materials with high impurity content and has strong versatility; the required auxiliary materials are few in variety, and the auxiliary materials are recycled in the process, and no wastewater or waste gas is generated, which has obvious environmental advantages; the purity of the obtained ammonium rhenate is above 99.995%, and the quality of the ammonium rhenate product is stable, and the rhenium metal recovery rate is higher than 99%; the process flow is short, and there is no need to increase the rhenium concentration in the ammonium rhenate solution by concentration, the energy consumption is low, and the process is highly controlled.

[0048] The above embodiments should not limit the present invention in any way, and any technical solutions obtained by equivalent replacement or equivalent conversion shall fall within the protection scope of the present invention.

Claims

1. A method for preparing high-purity ammonium rhenate from crude rhenate, characterized in that: Follow these steps: S1. preparing a crude rhenate solution, wherein the crude rhenate is crude ammonium rhenate or crude potassium rhenate, and 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. Prepare 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, stirring and reacting for 1-5 hours; centrifuging and filtering to obtain a rhenate filtrate; S4, adsorbing the rhenate filtrate obtained in step S3 using a cationic resin, and flowing out a rhenate solution after adsorption; S5, adding the rhenate solution treated in step S4 to a two-chamber bipolar membrane stack electrodialysis system; under the action of the DC electric field force, the water in the bipolar membrane dissociates to form H + , HO - , respectively migrate out from the positive membrane side and the negative membrane side of the bipolar membrane; the rhenate solution in the salt chamber undergoes bipolar membrane electrolysis, NH4 + or K + The OH migrates from the cation exchange membrane into the base chamber, thereby interacting with the OH migrated from the anion side of the bipolar membrane. - NH4OH or KOH is formed, and the salt chamber loses NH4 + or K + Get H + , so that the pH gradually decreases, and the pH of the salt chamber is controlled at 0-1 to obtain a perrhenic acid solution; S6. Under stirring conditions, add aqueous ammonia to the perrhenic acid solution obtained in step S5, and maintain the reaction temperature at -2 to 2°C; after the reaction is completed, centrifuge; wash and dry the solid phase 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 for preparing high-purity ammonium rhenate from crude rhenate according to claim 1, characterized in that: In step S3, the anion impurity content of the obtained rhenate filtrate is not higher than 30 mg / L.

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

5. The method for preparing high-purity ammonium rhenate from crude rhenate according to claim 1, characterized in that: In step S4, the cationic resin is a chelating resin of the MTS9300 brand; the adsorption linear velocity is 1-3 m / h.

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

7. The method for preparing high-purity ammonium rhenate from crude rhenate according to claim 1, characterized in that: 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 for preparing high-purity ammonium rhenate from crude rhenate according to claim 1, characterized in that: In step S6, the stirring frequency is 300-400 r / min.

9. The method for preparing high-purity ammonium rhenate from crude rhenate according to claim 1, characterized in that: In step S6, the mass percentage concentration of the ammonia water is 25-28%.

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

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