Process for separating zirconium from hafnium

Abstract

The present application relates to a kind of zirconium hafnium separation methods, comprising the following steps: taking zirconium compound to be separated, first hydrofluoric acid is added, and zirconium hafnium fluoride solution is obtained;The zirconium hafnium fluoride solution is extracted using extractant, and first zirconium fluoride aqueous solution and zirconium hafnium organic phase containing are obtained, and the extractant includes 10% of acidic phosphorus extractant and 90% of solvent by mass fraction.The above-mentioned zirconium hafnium separation method uses acidic phosphorus extractant to carry out extraction separation in hydrofluoric acid system, because the complex ion of hafnium is more stable than zirconium, so acidic phosphorus extractant extracts hafnium preferentially, and zirconium remains in aqueous phase, so that zirconium hafnium is separated, and the above-mentioned zirconium hafnium separation method is stable, and product purity is high.

Description

Technical Field

[0001] This invention relates to the field of chemical purification technology, and in particular to a method for separating zirconium and hafnium. Background Technology

[0002] Zirconium (Zr) has a very low thermal neutron absorption cross section, only 0.18 × 10⁻⁶. -28 m 2 When used as structural materials for nuclear reactors and as cladding materials for nuclear fuel, zirconium effectively avoids the absorption and waste of thermal neutrons, ensuring the efficient conduct of nuclear reactions. Therefore, zirconium metal and its alloys occupy an important position in the nuclear industry; their excellent nuclear properties, good corrosion resistance, and mechanical properties are currently irreplaceable by any other material.

[0003] Zirconium and hafnium (Hf) coexist in nature, but Hf has a large thermal neutron absorption cross section, exhibiting nuclear properties diametrically opposed to Zr. Therefore, only when the Hf content in Zr is below 0.01% can the requirements for nuclear reactor operation be met. However, apart from nuclear properties, Zr and Hf have very similar other physicochemical properties, making the separation of Zr and Hf extremely difficult. Summary of the Invention

[0004] Therefore, it is necessary to provide a zirconium-hafnium separation method to solve the problem of the difficulty in separating Zr and Hf.

[0005] A method for separating zirconium and hafnium includes the following steps:

[0006] Take the zirconium compound to be separated, add first hydrofluoric acid, and obtain a zirconium hafnium fluoride solution;

[0007] The zirconium hafnium fluoride solution is extracted using an extractant to obtain a zirconium hafnium-containing organic phase and a first zirconium fluoride aqueous solution. The extractant comprises 10%-30% by mass of an acidic phosphorus extractant and 70%-90% by mass of a solvent.

[0008] In one embodiment, the zirconium compound to be separated is at least one of zirconium oxychloride and zirconium oxide.

[0009] In one embodiment, the acidity of the zirconium hafnium fluoride solution is 0.2-1.0 mol / L.

[0010] In one embodiment, the concentration of the first hydrofluoric acid is 1-4 mol / L.

[0011] In one embodiment, the volume ratio of the extractant to the zirconium hafnium fluoride solution is 5-6:1.

[0012] In one embodiment, the solvent comprises 10%-20% octanol and 50%-70% sulfonated kerosene as a mass fraction of the extractant.

[0013] In one embodiment, the extraction process has 90-120 stages.

[0014] In one embodiment, the zirconium-hafnium separation method further includes the following steps:

[0015] Adding a first alkaline solution to the first zirconium fluoride aqueous solution yields a zirconium-containing precipitate.

[0016] The zirconium-containing precipitate is subjected to a first water washing treatment to obtain a water-washed zirconium-containing precipitate;

[0017] The water-washed zirconium-containing precipitate was subjected to a first calcination treatment to obtain zirconium oxide.

[0018] In one embodiment, the first alkaline solution is selected from at least one of sodium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium carbonate solution, ammonium bicarbonate solution, and ammonia water.

[0019] In one embodiment, the concentration of the first alkaline solution is 2-3 mol / L.

[0020] In one embodiment, the mass ratio of the first zirconium fluoride aqueous solution to the first alkaline solution is (0.2~0.25):1.

[0021] In one embodiment, the temperature of the first calcination treatment is 800-900°C.

[0022] In one embodiment, the zirconium-hafnium separation method further includes the following steps:

[0023] The zirconium-containing hafnium organic phase was washed with a second hydrofluoric acid to obtain a second zirconium fluoride aqueous solution and a hafnium-containing organic phase.

[0024] In one embodiment, the concentration of the second hydrofluoric acid is 1 mol / L to 4 mol / L.

[0025] In one embodiment, the volume ratio of the zirconium-containing hafnium organic phase to the second hydrofluoric acid is (0.9~4.1):1.

[0026] In one embodiment, the number of washing stages is 50-60.

[0027] In one embodiment, the zirconium-hafnium separation method further includes the following steps:

[0028] The hafnium-containing organic phase was back-extracted using third hydrofluoric acid to obtain an aqueous solution of hafnium fluoride and a blank organic phase.

[0029] In one embodiment, the concentration of the third hydrofluoric acid is 1 mol / L to 4 mol / L.

[0030] In one embodiment, the volume ratio of the hafnium-containing organic phase to the third hydrofluoric acid is (7.5~60):1.

[0031] In one embodiment, the number of stages of the back-extraction process is 10-20.

[0032] In one embodiment, the zirconium-hafnium separation method further includes the following steps:

[0033] A second alkaline solution was added to the hafnium fluoride aqueous solution to obtain a hafnium-containing precipitate;

[0034] The hafnium-containing precipitate was subjected to a second water washing treatment to obtain a water-washed hafnium-containing precipitate;

[0035] The water-washed hafnium-containing precipitate was subjected to a second calcination treatment to obtain hafnium oxide.

[0036] In one embodiment, the second alkaline solution is selected from at least one of sodium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium carbonate solution, ammonium bicarbonate solution, and ammonia water.

[0037] In one embodiment, the concentration of the second alkaline solution is 2-3 mol / L.

[0038] In one embodiment, the mass ratio of the hafnium fluoride aqueous solution to the second alkaline solution is (0.4~0.45):1.

[0039] In one embodiment, the temperature of the second calcination treatment is 800-900°C.

[0040] Compared with traditional methods, the above-mentioned zirconium-hafnium separation method has the following advantages:

[0041] The above-mentioned zirconium-hafnium separation method involves extracting the zirconium compound to be separated in a hydrofluoric acid system using an acidic phosphorus extractant. Since the complex ion of hafnium is more stable than that of zirconium, the acidic phosphorus extractant preferentially extracts hafnium, leaving zirconium in the aqueous phase, thus separating zirconium and hafnium. The hydrofluoric acid system has a large separation coefficient, and the system is stable after separation, resulting in a high back-extraction rate. The above-mentioned zirconium-hafnium separation method provides stable zirconium-hafnium separation and high product purity. Detailed Implementation

[0042] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] A zirconium-hafnium separation method according to an embodiment of the present invention includes the following steps:

[0045] Step S11: Take the zirconium compound to be separated, add the first hydrofluoric acid, and obtain a zirconium hafnium fluoride solution.

[0046] Optionally, the zirconium compound to be separated can be, but is not limited to, at least one of zirconium oxychloride and zirconium oxide.

[0047] Optionally, the acidity of the zirconium hafnium fluoride solution is 0.2-1.0 mol / L.

[0048] Step S12: The zirconium hafnium fluoride solution is extracted with an extractant to obtain a zirconium hafnium organic phase and a first zirconium fluoride aqueous solution. The extractant includes an acidic phosphorus extractant with a mass fraction of 10%-30% and a solvent with a mass fraction of 70%-90%.

[0049] Optionally, the volume ratio of the extractant to the zirconium hafnium fluoride solution is 5-6:1.

[0050] In one example, the solvent comprises 10%-20% octanol and 50%-70% sulfonated kerosene as a mass fraction of the extractant.

[0051] Optionally, the number of extraction stages is 90-120.

[0052] In one example, the zirconium-hafnium separation method further includes the following steps:

[0053] Step S21: Add a first alkaline solution to the first zirconium fluoride aqueous solution to obtain a zirconium-containing precipitate.

[0054] Optionally, the first alkaline solution may be, but is not limited to, at least one of sodium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium carbonate solution, ammonium bicarbonate solution, and ammonia water.

[0055] Optionally, the concentration of the first alkaline solution is 2-3 mol / L.

[0056] Optionally, the mass ratio of the first zirconium fluoride aqueous solution to the first alkaline solution is (0.2~0.25):1.

[0057] Step S22: Perform a first water washing treatment on the zirconium-containing precipitate to obtain a water-washed zirconium-containing precipitate.

[0058] After step S22, the alkaline solution in the zirconium-containing precipitate is washed away, improving the purity of the product. The mother liquor and wash water can be concentrated and crystallized to obtain fluoride byproducts.

[0059] Step S23: The water-washed zirconium-containing precipitate is subjected to a first calcination treatment to obtain zirconium oxide.

[0060] Optionally, the temperature of the first calcination treatment is 800-900℃. The duration of the first calcination treatment is 2-4 hours.

[0061] In one example, the zirconium-hafnium separation method further includes the following steps:

[0062] Step S31: The zirconium-containing hafnium organic phase is washed with a second hydrofluoric acid to obtain a second zirconium fluoride aqueous solution and a hafnium-containing organic phase.

[0063] After step S31, 99.99% of the zirconium in the zirconium-hafnium organic phase is transferred to the aqueous phase, thus purifying the zirconium-hafnium organic phase to obtain the hafnium-containing organic phase.

[0064] Optionally, the concentration of the second hydrofluoric acid is 1 mol / L to 4 mol / L. In some specific examples, the concentration of the second hydrofluoric acid is 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, etc.

[0065] Optionally, the volume ratio of the zirconium-containing hafnium organic phase to the second hydrofluoric acid is (0.9~4.1):1. In some specific examples, the volume ratio of the zirconium-containing hafnium organic phase to the second hydrofluoric acid is 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, etc.

[0066] Optionally, the number of washing stages is 50-60.

[0067] In one example, the zirconium-hafnium separation method further includes the following steps:

[0068] Step S41: The hafnium-containing organic phase is back-extracted using third hydrofluoric acid to obtain an aqueous hafnium fluoride solution and a blank organic phase.

[0069] After step S41, approximately 99.99% of the hafnium in the hafnium-containing organic phase is transferred to the aqueous phase.

[0070] Optionally, the concentration of the third hydrofluoric acid is 1 mol / L to 4 mol / L. In some specific examples, the concentration of the third hydrofluoric acid is 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, etc.

[0071] Optionally, the volume ratio of the hafnium-containing organic phase to the third hydrofluoric acid is (7.5~60):1. In some specific examples, the volume ratio of the hafnium-containing organic phase to the third hydrofluoric acid is 10:1, 15:1, 20:1, 25:1, 30:1, 40:1, 50:1, etc.

[0072] Optionally, the number of back-extraction stages is 10-20.

[0073] The blank organic phase can be washed with water at a volume ratio of (8~12):1. The washed blank organic phase can be recycled as an extractant. The wash water can be concentrated and crystallized to obtain fluoride byproducts.

[0074] In one example, the zirconium-hafnium separation method further includes the following steps:

[0075] Step S51: Add a second alkaline solution to the hafnium fluoride aqueous solution to obtain a hafnium-containing precipitate.

[0076] Optionally, the second alkaline solution may be, but is not limited to, at least one of sodium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium carbonate solution, ammonium bicarbonate solution, and ammonia water.

[0077] Optionally, the concentration of the second alkali solution is 2-3 mol / L.

[0078] Optionally, the mass ratio of hafnium fluoride aqueous solution to the second alkaline solution is (0.4~0.45):1.

[0079] Step S52: Perform a second water washing treatment on the hafnium-containing precipitate to obtain water-washed hafnium-containing precipitate.

[0080] After step S52, the alkaline solution in the hafnium-containing precipitate is washed away, improving the purity of the product. The mother liquor and wash water can be concentrated and crystallized to obtain fluoride byproducts.

[0081] Step S53: The hafnium-containing precipitate washed with water is subjected to a second calcination treatment to obtain hafnium oxide.

[0082] Optionally, the temperature of the second calcination treatment is 800-900℃. The duration of the second calcination treatment is 2-4 hours.

[0083] The above-mentioned zirconium-hafnium separation method involves extracting and separating the zirconium compound to be separated in a hydrofluoric acid system using an acidic phosphorus extractant. Since the complex ion of hafnium is more stable than that of zirconium, the acidic phosphorus extractant preferentially extracts hafnium, while zirconium remains in the aqueous phase, thus separating zirconium and hafnium. The hydrofluoric acid system has a large separation coefficient, the system is stable after separation, the back-extraction rate is high, the zirconium-hafnium separation is stable, and the product purity is high.

[0084] The above-mentioned zirconium-hafnium separation method also has the advantages of low initial investment cost, low operating cost, convenient equipment operation and maintenance, and simple, advanced and reliable process.

[0085] The following specific embodiments further illustrate the zirconium-hafnium separation method of the present invention.

[0086] Example 1

[0087] The zirconium-hafnium separation method in this embodiment includes the following steps:

[0088] Step 1: Take the zirconium oxychloride to be separated, add hydrofluoric acid, and prepare a zirconium hafnium fluoride solution with a zirconium content of 100 g / L, a hafnium content of 2 g / L, and an acidity of 1.0 mol / L.

[0089] Step 2: Acidic phosphorus extractant P507, sulfonated kerosene, and isooctanol were mixed in a volume ratio of 1:7:2 to obtain an extractant. This extractant was then used to extract the zirconium hafnium fluoride solution from Step 1. The volume ratio of the extractant to the zirconium hafnium fluoride solution was 6:1, the mixing time was 5 minutes, and the extraction stage was 35 stages. Sampling and analysis showed that 99.99% of the hafnium and 13.96% of the zirconium in the zirconium hafnium fluoride solution were extracted into the organic phase, resulting in a zirconium-containing hafnium organic phase. The aqueous phase was an aqueous solution of zirconium fluoride.

[0090] Step 3: The zirconium-hafnium organic phase from Step 2 is washed with a hydrofluoric acid washing solution with an acidity of 1.0 mol / L. The volume ratio of the zirconium-hafnium organic phase to the hydrofluoric acid washing solution is 3:1. Each wash lasts 5 minutes, and the washes are repeated 55 times. 99.99% of the zirconium in the zirconium-hafnium organic phase is transferred to the aqueous phase, resulting in a zirconium fluoride aqueous solution and a hafnium organic phase.

[0091] Step 4: Hydrofluoric acid with an acidity of 1.0 mol / L is used as the back-extraction solution to back-extract the hafnium-containing organic phase from Step 3. The volume ratio of the hafnium-containing organic phase to the hydrofluoric acid back-extraction solution is 15:1, the mixing time is 5 min, and the back-extraction stage is 16 stages, so that 99.99% of the hafnium in the hafnium-containing organic phase is transferred to the aqueous phase, yielding a hafnium fluoride aqueous solution and a blank organic phase.

[0092] Step 5: Add 2 mol / L NaOH solution to the zirconium fluoride aqueous solution from Step 2, control the endpoint pH to 8, and obtain a zirconium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the zirconium-containing precipitate at 850℃ to obtain zirconium oxide (where ZrO2 purity is 99.996% and HfO2 content is 0.002%).

[0093] Step 6: Add 2 mol / L NaOH solution to the hafnium fluoride aqueous solution from Step 4, control the endpoint pH to 8, and obtain a hafnium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the hafnium-containing precipitate at 850℃ to obtain hafnium oxide (where the purity of HfO2 is 99.997% and the content of ZrO2 is 0.001%).

[0094] Step 7: Wash the blank organic phase from Step 4 with water 4 times. It can be recycled as an extractant.

[0095] Step 8: Concentrate and crystallize the precipitate mother liquor and washing solution from Step 5, and concentrate and crystallize the precipitate mother liquor and washing solution from Step 6 to obtain fluoride by-products.

[0096] Example 2

[0097] The zirconium-hafnium separation method in this embodiment includes the following steps:

[0098] Step 1: Take the zirconium oxychloride to be separated, add hydrofluoric acid, and prepare a zirconium hafnium fluoride solution with a zirconium content of 100 g / L, a hafnium content of 2.1 g / L, and an acidity of 1.0 mol / L.

[0099] Step 2: Acidic phosphorus extractant P507, sulfonated kerosene, and isooctanol were mixed in a volume ratio of 2:6:2 to obtain an extractant. This extractant was then used to extract the zirconium hafnium fluoride solution from Step 1. The volume ratio of the extractant to the zirconium hafnium fluoride solution was 3:1, the mixing time was 5 minutes, and the extraction stage was 35 stages. Sampling and analysis showed that 99.99% of the hafnium and 14.11% of the zirconium in the zirconium hafnium fluoride solution were extracted into the organic phase, resulting in a zirconium-containing hafnium organic phase. The aqueous phase was an aqueous solution of zirconium fluoride.

[0100] Step 3: The zirconium-hafnium organic phase from Step 2 is washed with a hydrofluoric acid washing solution with an acidity of 1.0 mol / L. The volume ratio of the zirconium-hafnium organic phase to the hydrofluoric acid washing solution is 2:1. Each wash lasts 5 minutes, and the washes are repeated 55 times. 99.99% of the zirconium in the zirconium-hafnium organic phase is transferred to the aqueous phase, resulting in a zirconium fluoride aqueous solution and a hafnium organic phase.

[0101] Step 4: Hydrofluoric acid with an acidity of 1.0 mol / L is used as the back-extraction solution to back-extract the hafnium-containing organic phase from Step 3. The volume ratio of the hafnium-containing organic phase to the hydrofluoric acid back-extraction solution is 7.5:1, the mixing time is 5 min, and the back-extraction stage is 16 stages, so that 99.99% of the hafnium in the hafnium-containing organic phase is transferred to the aqueous phase, yielding a hafnium fluoride aqueous solution and a blank organic phase.

[0102] Step 5: Add 2 mol / L NaOH solution to the zirconium fluoride aqueous solution from Step 2, control the endpoint pH to 8, and obtain a zirconium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the zirconium-containing precipitate at 850℃ to obtain zirconium oxide (where ZrO2 purity is 99.997% and HfO2 content is 0.001%).

[0103] Step 6: Add 2 mol / L NaOH solution to the hafnium fluoride aqueous solution from Step 4, control the endpoint pH to 8, and obtain a hafnium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the hafnium-containing precipitate at 850℃ to obtain hafnium oxide (where the purity of HfO2 is 99.996% and the content of ZrO2 is 0.002%).

[0104] Step 7: Wash the blank organic phase from Step 4 with water 4 times. It can be recycled as an extractant.

[0105] Step 8: Concentrate and crystallize the precipitate mother liquor and washing solution from Step 5, and concentrate and crystallize the precipitate mother liquor and washing solution from Step 6 to obtain fluoride by-products.

[0106] Example 3

[0107] The zirconium-hafnium separation method in this embodiment includes the following steps:

[0108] Step 1: Take the zirconium oxychloride to be separated, add hydrofluoric acid, and prepare a zirconium hafnium fluoride solution with a zirconium content of 100 g / L, a hafnium content of 2.1 g / L, and an acidity of 1.0 mol / L.

[0109] Step 2: Acidic phosphorus extractant P507, sulfonated kerosene, and isooctanol were mixed in a volume ratio of 3:5:2 to obtain an extractant. This extractant was then used to extract the zirconium hafnium fluoride solution from Step 1. The volume ratio of the extractant to the zirconium hafnium fluoride solution was 2:1, the mixing time was 5 minutes, and the extraction stage was 35 stages. Sampling and analysis showed that 99.99% of the hafnium and 14.31% of the zirconium in the zirconium hafnium fluoride solution were extracted into the organic phase, resulting in a zirconium-containing hafnium organic phase. The aqueous phase was an aqueous solution of zirconium fluoride.

[0110] Step 3: The zirconium-hafnium organic phase from Step 2 is washed with a hydrofluoric acid washing solution with an acidity of 1.0 mol / L. The volume ratio of the zirconium-hafnium organic phase to the hydrofluoric acid washing solution is 3:1. Each wash lasts 5 minutes, and the washes are repeated 55 times. 99.99% of the zirconium in the zirconium-hafnium organic phase is transferred to the aqueous phase, resulting in a zirconium fluoride aqueous solution and a hafnium organic phase.

[0111] Step 4: Hydrofluoric acid with an acidity of 1.0 mol / L is used as the back-extraction solution to back-extract the hafnium-containing organic phase from Step 3. The volume ratio of the hafnium-containing organic phase to the hydrofluoric acid back-extraction solution is 5:1, the mixing time is 5 min, and the back-extraction stage is 16 stages, so that 99.99% of the hafnium in the hafnium-containing organic phase is transferred to the aqueous phase, yielding a hafnium fluoride aqueous solution and a blank organic phase.

[0112] Step 5: Add 2 mol / L NaOH solution to the zirconium fluoride aqueous solution from Step 2, control the endpoint pH to 8, and obtain a zirconium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the zirconium-containing precipitate at 850℃ to obtain zirconium oxide (where ZrO2 purity is 99.998% and HfO2 content is 0.001%).

[0113] Step 6: Add 2 mol / L NaOH solution to the hafnium fluoride aqueous solution from Step 4, control the endpoint pH to 8, and obtain a hafnium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the hafnium-containing precipitate at 850℃ to obtain hafnium oxide (where the purity of HfO2 is 99.995% and the content of ZrO2 is 0.003%).

[0114] Step 7: Wash the blank organic phase from Step 4 with water 4 times. It can be recycled as an extractant.

[0115] Step 8: Concentrate and crystallize the precipitate mother liquor and washing solution from Step 5, and concentrate and crystallize the precipitate mother liquor and washing solution from Step 6 to obtain fluoride by-products.

[0116] Example 4

[0117] The zirconium-hafnium separation method in this embodiment includes the following steps:

[0118] Step 1: Take the zirconium oxychloride to be separated, add hydrofluoric acid, and prepare a zirconium hafnium fluoride solution with a zirconium content of 150 g / L, a hafnium content of 3 g / L, and an acidity of 0.6 mol / L.

[0119] Step 2: Acidic phosphorus extractant P507, sulfonated kerosene, and isooctanol were mixed at a volume ratio of 1:7:2 to obtain an extractant. This extractant was then used to extract the zirconium hafnium fluoride solution from Step 1. The volume ratio of the extractant to the zirconium hafnium fluoride solution was 9:1, the mixing time was 5 minutes, and the extraction stage was 35 stages. Sampling and analysis showed that 99.99% of the hafnium and 14.20% of the zirconium in the zirconium hafnium fluoride solution were extracted into the organic phase, resulting in a zirconium-containing hafnium organic phase. The aqueous phase was an aqueous solution of zirconium fluoride.

[0120] Step 3: The zirconium-hafnium organic phase from Step 2 was washed with a hydrofluoric acid washing solution with an acidity of 1.5 mol / L. The volume ratio of the zirconium-hafnium organic phase to the hydrofluoric acid washing solution was 3:1. Each wash lasted 5 minutes, and the washes were repeated 55 times. 99.99% of the zirconium in the zirconium-hafnium organic phase was transferred to the aqueous phase, resulting in a zirconium fluoride aqueous solution and a hafnium organic phase.

[0121] Step 4: Hydrofluoric acid with an acidity of 1.5 mol / L is used as the back-extraction solution to back-extract the hafnium-containing organic phase from Step 3. The volume ratio of the hafnium-containing organic phase to the hydrofluoric acid back-extraction solution is 10:1, the mixing time is 5 min, and the back-extraction stage is 16 stages, so that 99.99% of the hafnium in the hafnium-containing organic phase is transferred to the aqueous phase, yielding a hafnium fluoride aqueous solution and a blank organic phase.

[0122] Step 5: Add 2 mol / L NaOH solution to the zirconium fluoride aqueous solution from Step 2, control the endpoint pH to 8, and obtain a zirconium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the zirconium-containing precipitate at 850℃ to obtain zirconium oxide (where ZrO2 purity is 99.995% and HfO2 content is 0.003%).

[0123] Step 6: Add 2 mol / L NaOH solution to the hafnium fluoride aqueous solution from Step 4, control the endpoint pH to 8, and obtain a hafnium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the hafnium-containing precipitate at 850℃ to obtain hafnium oxide (where the purity of HfO2 is 99.996% and the content of ZrO2 is 0.002%).

[0124] Step 7: Wash the blank organic phase from Step 4 with water 4 times. It can be recycled as an extractant.

[0125] Step 8: Concentrate and crystallize the precipitate mother liquor and washing solution from Step 5, and concentrate and crystallize the precipitate mother liquor and washing solution from Step 6 to obtain fluoride by-products.

[0126] Example 5

[0127] The zirconium-hafnium separation method in this embodiment includes the following steps:

[0128] Step 1: Take the zirconium oxychloride to be separated, add hydrofluoric acid, and prepare a zirconium hafnium fluoride solution with a zirconium content of 150 g / L, a hafnium content of 3 g / L, and an acidity of 0.6 mol / L.

[0129] Step 2: Acidic phosphorus extractant P507, sulfonated kerosene, and isooctanol were mixed at a volume ratio of 1:7:2 to obtain an extractant. This extractant was then used to extract the zirconium fluoride hafnium solution from Step 1. The volume ratio of the extractant to the zirconium fluoride hafnium solution was 9:1, the mixing time was 5 minutes, and the extraction stage was 35 stages. Sampling and analysis showed that 99.99% of the hafnium and 14.15% of the zirconium in the zirconium fluoride hafnium solution were extracted into the organic phase, resulting in a zirconium-containing hafnium organic phase. The aqueous phase was an aqueous solution of zirconium fluoride.

[0130] Step 3: The zirconium-hafnium organic phase from Step 2 was washed with a hydrofluoric acid washing solution with an acidity of 4.0 mol / L. The volume ratio of the zirconium-hafnium organic phase to the hydrofluoric acid washing solution was 8:1. Each wash lasted 5 minutes, and the washes were repeated 55 times. 99.99% of the zirconium in the zirconium-hafnium organic phase was transferred to the aqueous phase, resulting in a zirconium fluoride aqueous solution and a hafnium organic phase.

[0131] Step 4: Hydrofluoric acid with an acidity of 4.0 mol / L is used as the back-extraction solution to back-extract the hafnium-containing organic phase from Step 3. The volume ratio of the hafnium-containing organic phase to the hydrofluoric acid back-extraction solution is 26:1, the mixing time is 5 min, and the back-extraction stage is 16 stages, so that 99.99% of the hafnium in the hafnium-containing organic phase is transferred to the aqueous phase, yielding a hafnium fluoride aqueous solution and a blank organic phase.

[0132] Step 5: Add 2 mol / L NaOH solution to the zirconium fluoride aqueous solution from Step 2, control the endpoint pH to 8, and obtain a zirconium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the zirconium-containing precipitate at 850℃ to obtain zirconium oxide (where ZrO2 purity is 99.997% and HfO2 content is 0.001%).

[0133] Step 6: Add 2 mol / L NaOH solution to the hafnium fluoride aqueous solution from Step 4, control the endpoint pH to 8, and obtain a hafnium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the hafnium-containing precipitate at 850℃ to obtain hafnium oxide (where the purity of HfO2 is 99.996% and the content of ZrO2 is 0.002%).

[0134] Step 7: Wash the blank organic phase from Step 4 with water 4 times. It can be recycled as an extractant.

[0135] Step 8: Concentrate and crystallize the precipitate mother liquor and washing solution from Step 5, and concentrate and crystallize the precipitate mother liquor and washing solution from Step 6 to obtain fluoride by-products.

[0136] Example 6

[0137] The zirconium-hafnium separation method in this embodiment includes the following steps:

[0138] Step 1: Take the zirconium oxychloride to be separated, add hydrofluoric acid, and prepare a zirconium hafnium fluoride solution with a zirconium content of 200 g / L, a hafnium content of 4 g / L, and an acidity of 0.2 mol / L.

[0139] Step 2: Acidic phosphorus extractant P507, sulfonated kerosene, and isooctanol were mixed at a volume ratio of 1:7:2 to obtain an extractant. This extractant was then used to extract the zirconium hafnium fluoride solution from Step 1. The volume ratio of the extractant to the zirconium hafnium fluoride solution was 12:1, the mixing time was 5 minutes, and the extraction stage was 35 stages. Sampling and analysis showed that 99.99% of the hafnium and 13.80% of the zirconium in the zirconium hafnium fluoride solution were extracted into the organic phase, resulting in a zirconium-containing hafnium organic phase. The aqueous phase was an aqueous solution of zirconium fluoride.

[0140] Step 3: The zirconium-hafnium organic phase from Step 2 was washed with a hydrofluoric acid washing solution with an acidity of 4.0 mol / L. The volume ratio of the zirconium-hafnium organic phase to the hydrofluoric acid washing solution was 8:1. Each wash lasted 5 minutes, and the washes were repeated 55 times. 99.99% of the zirconium in the zirconium-hafnium organic phase was transferred to the aqueous phase, resulting in a zirconium fluoride aqueous solution and a hafnium organic phase.

[0141] Step 4: Hydrofluoric acid with an acidity of 4.0 mol / L is used as the back-extraction solution to back-extract the hafnium-containing organic phase from Step 3. The volume ratio of the hafnium-containing organic phase to the hydrofluoric acid back-extraction solution is 26:1, the mixing time is 5 min, and the back-extraction stage is 16 stages, so that 99.99% of the hafnium in the hafnium-containing organic phase is transferred to the aqueous phase, yielding a hafnium fluoride aqueous solution and a blank organic phase.

[0142] Step 5: Add 2 mol / L NaOH solution to the zirconium fluoride aqueous solution from Step 2, control the endpoint pH to 8, and obtain a zirconium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the zirconium-containing precipitate at 850℃ to obtain zirconium oxide (where ZrO2 purity is 99.995% and HfO2 content is 0.003%).

[0143] Step 6: Add 2 mol / L NaOH solution to the hafnium fluoride aqueous solution from Step 4, control the endpoint pH to 8, and obtain a hafnium-containing precipitate. Wash with water until the pH reaches 7. Calcinate the hafnium-containing precipitate at 850℃ to obtain hafnium oxide (where the purity of HfO2 is 99.997% and the content of ZrO2 is 0.001%).

[0144] Step 7: Wash the blank organic phase from Step 4 with water 4 times. It can be recycled as an extractant.

[0145] Step 8: Concentrate and crystallize the precipitate mother liquor and washing solution from Step 5, and concentrate and crystallize the precipitate mother liquor and washing solution from Step 6 to obtain fluoride by-products.

[0146] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0147] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for separating zirconium and hafnium, characterized in that, Includes the following steps: Take the zirconium compound to be separated, add first hydrofluoric acid, and obtain a zirconium hafnium fluoride solution; The zirconium compound to be separated is at least one of zirconium oxychloride and zirconium oxide, the acidity of the zirconium hafnium fluoride solution is 0.2-1.0 mol / L, and the concentration of the first hydrofluoric acid is 1-4 mol / L; The zirconium hafnium fluoride solution is extracted using an extractant to obtain a zirconium hafnium-containing organic phase and a first zirconium fluoride aqueous solution. The extractant comprises 10%-30% by mass of an acidic phosphorus extractant and 70%-90% by mass of a solvent. The solvent comprises 10%-20% by mass of octanol and 50%-70% by mass of sulfonated kerosene. The volume ratio of the extractant to the zirconium hafnium fluoride solution is 5-6:1, and the number of extraction stages is 90-120. A first alkaline solution is added to the first zirconium fluoride aqueous solution to obtain a zirconium-containing precipitate. The concentration of the first alkaline solution is 2-3 mol / L, and the mass ratio of the first zirconium fluoride aqueous solution to the first alkaline solution is (0.2~0.25):

1. The zirconium-containing precipitate is subjected to a first water washing treatment to obtain a water-washed zirconium-containing precipitate; The water-washed zirconium-containing precipitate is subjected to a first calcination treatment at a temperature of 800-900℃ to obtain zirconium oxide. The zirconium-hafnium separation method further includes the following steps: The zirconium-containing hafnium organic phase was washed with a second hydrofluoric acid to obtain a second zirconium fluoride aqueous solution and a hafnium-containing organic phase. The hafnium-containing organic phase was back-extracted using hydrofluoric acid to obtain an aqueous hafnium fluoride solution and a blank organic phase. A second alkaline solution was added to the hafnium fluoride aqueous solution to obtain a hafnium-containing precipitate; The hafnium-containing precipitate was subjected to a second water washing treatment to obtain a water-washed hafnium-containing precipitate; The water-washed hafnium-containing precipitate was subjected to a second calcination treatment to obtain hafnium oxide; The concentration of the second hydrofluoric acid is 1 mol / L to 4 mol / L, the volume ratio of the zirconium-containing hafnium organic phase to the second hydrofluoric acid is (0.9~4.1):1, and the number of washing stages is 50-60; the concentration of the third hydrofluoric acid is 1 mol / L to 4 mol / L, the volume ratio of the hafnium-containing organic phase to the third hydrofluoric acid is (7.5~60):1, and the number of back-extraction stages is 10-20; the concentration of the second alkaline solution is 2-3 mol / L, the mass ratio of the hafnium fluoride aqueous solution to the second alkaline solution is (0.4~0.45):1, and the temperature of the second calcination treatment is 800-900℃.

2. The zirconium-hafnium separation method as described in claim 1, characterized in that, The first alkaline solution is selected from at least one of sodium hydroxide solution, ammonia water, sodium carbonate, sodium bicarbonate, ammonium carbonate, and ammonium bicarbonate.

3. The zirconium-hafnium separation method as described in claim 1, characterized in that, The second alkaline solution is selected from at least one of sodium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium carbonate solution, ammonium bicarbonate solution, and ammonia water.