Method for separating zirconium and hafnium through solvent extraction

Abstract

The invention relates to a method for separating zirconium and hafnium through solvent extraction, and belongs to the technical field of hydrometallurgy. According to the method, zirconium and hafnium separation is achieved through a solvent extraction method, the novel extraction agent is adopted, the synergistic effect of the modified imidazole ionic liquid, the amide compound and tributyl phosphate is utilized, the process steps of solution acidification, extraction agent extraction, sulfuric acid solution washing and reverse extraction are carried out, and the zirconium solution and the hafnium solution are obtained through separation. The process method is simple, the separation effect is good, and the separation purity is high.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy and relates to a method for separating zirconium and hafnium through solvent extraction. Background Art

[0002] The physical and chemical properties of zirconium and hafnium are very similar, and zirconium and hafnium always coexist in nature, and there is no separate zirconium ore or hafnium ore. Therefore, in order to obtain nuclear-grade zirconium and nuclear-grade hafnium, they must be separated.

[0003] Among the separation methods currently under study, the main separation method is wet separation, among which the solvent extraction method uses the different solubility of different compounds formed by zirconium and hafnium in different acid media in the extraction organic phase or the different binding abilities with the extractant to achieve separation.

[0004] Solvent extraction is one of the most widely used methods for extracting and separating zirconium and hafnium in industry. It has the advantages of easy operation, simple process and large processing capacity. At present, the main disadvantages of using traditional extraction systems to extract zirconium and hafnium are: easy emulsification, serious corrosion of production equipment, and the use of a large amount of volatile organic solvents. The large amount of volatilization of organic solvents not only hinders the recycling of the extracted organic phase and increases the production cost, but also easily causes environmental pollution.

[0005] Therefore, it is necessary to find new solvent extraction systems to avoid the shortcomings of traditional extraction systems. Summary of the invention

[0006] The object of the present invention is to provide a method for separating zirconium and hafnium by solvent extraction. The process of the present invention is simple, the separation effect is good, and the separation purity is high.

[0007] The purpose of the present invention can be achieved through the following technical solutions: 1. A method for separating zirconium and hafnium by solvent extraction, comprising the following steps: S1. Add zirconium oxychloride or zirconium tetrachloride into pure water, filter until the filtrate is clear and transparent after it is completely dissolved, then add concentrated hydrochloric acid to adjust the acidity of the aqueous phase, and stir to obtain an aqueous phase solution, so that the concentration of hydrochloric acid in the aqueous phase solution is 6-8 mol / L, and the concentration of zirconium ions in the aqueous phase solution is 20-50 g / L; S2. At 50-55°C, allyl chloride and methyl imidazole in a molar ratio of 1.5:1 were refluxed with magnetic stirring for 8-10 hours, and the ionic liquid 1-allyl-3-methylimidazolium chloride AMIMCl was obtained by distillation and rotary evaporation. AMIMCl was dissolved in ethyl acetate, and vinyl triethoxysilane was added after mixing evenly. After stirring evenly, methyl stearate was added and stirred evenly. After standing for 10-12 hours, it was heated to 55-65°C and stirred for 3-5 hours to obtain a modified ionic liquid, wherein the volume ratio of AMIMCl, ethyl acetate and vinyl triethoxysilane was 1: (3-5): (0.1-0.15); The modified ionic liquid, amide compound and tributyl phosphate in a volume ratio of (0.1-0.2):2:(6-10) are fully mixed to obtain an extract, and then a diluent is added to prepare an organic phase solution, wherein the volume ratio of the extract to the diluent is (1-3):(3-5); S3, extracting by countercurrent chromatography, using the aqueous phase solution obtained in step S1 as the aqueous phase, and the organic phase solution obtained in step S2 as the organic phase, first filling the internal pipeline of the countercurrent chromatography with the organic phase, and then injecting the organic phase and the aqueous phase simultaneously, wherein the volume ratio of the organic phase to the aqueous phase during the simultaneous injection process is 2: (1-2.5), extracting zirconium in the aqueous phase into the organic phase to obtain an organic phase containing zirconium, and leaving hafnium in the aqueous phase; S4, washing the zirconium-containing organic phase with a detergent, first filling the internal pipeline of the countercurrent chromatograph with the detergent, and then injecting the detergent and the zirconium-containing organic phase simultaneously, with the detergent serving as the aqueous phase. During the simultaneous injection process, the ratio of the zirconium-containing organic phase to the detergent is 2:(3-4), thereby obtaining a zirconium-rich organic phase; S5. Use pure water as the water phase to perform back extraction on the zirconium-rich organic phase, the ratio of pure water to the zirconium-rich organic phase is 5:1, and a zirconium-containing solution is obtained.

[0008] As a preferred technical solution of the present invention, in step S2, the diluent is one of n-octane, sulfonated kerosene, toluene and a mixed solution of n-octane and n-octanol in a volume ratio of 9:1.

[0009] As a preferred technical solution of the present invention, in step S2, the amide compound includes one of N,N,N',N'-tetrabutylmalonamide, N,N-dimethylbenzamide, N,N,N,N-tetraalkylpyridinediamide and N-alkylcaprolactam.

[0010] As a preferred technical solution of the present invention, in step S3, during the extraction, during the simultaneous injection of the organic phase and the aqueous phase, the temperature of the countercurrent chromatograph is 30-50°C, the processing time is 30-60min, and the rotation speed of the countercurrent chromatograph is 300-400rpm, wherein the flow rate of the organic phase during the simultaneous injection process is 200 mL / min, and the flow rate of the aqueous phase is 100-250 mL / min.

[0011] As a preferred technical solution of the present invention, in step S4, the detergent is a 5-6 mol / L sulfuric acid solution.

[0012] As a preferred technical solution of the present invention, in step S4, during the simultaneous injection process, the temperature of the countercurrent chromatograph is 25~45°C, the processing time is 30~50min, the rotation speed of the countercurrent chromatograph is 300~400rpm, wherein during the simultaneous injection process, the flow rate of the organic phase is 200 mL / min, and the flow rate of the aqueous phase is 300~400mL / min.

[0013] As a preferred technical solution of the present invention, in step S5, the temperature during back extraction with pure water is 20-40°C, the time is 15-30 min, the rotation speed of the countercurrent chromatograph is 300-400 rpm, the flow rate of the zirconium-rich organic phase is 100 mL / min, and the flow rate of the aqueous phase is 500 mL / min.

[0014] The present invention separates zirconium and hafnium by solvent extraction. Zirconium and hafnium are derived from zirconium oxychloride or zirconium tetrachloride. Zirconium and hafnium are symbiotic in nature and are difficult to separate by conventional methods. In the process of preparing zirconium oxychloride or zirconium tetrachloride, hafnium will enter zirconium oxychloride or zirconium tetrachloride at the same time, resulting in these compounds also containing hafnium. Therefore, zirconium ions and hafnium ions exist simultaneously in the aqueous phase solution prepared in step S1. Acidification of the raw material (zirconium oxychloride or zirconium tetrachloride) with an inorganic acid is helpful for dissolving and extracting metal ions. The pH value of the solution is accurately adjusted by hydrochloric acid to keep the solution within the optimal extraction pH range. At the same time, the addition of hydrochloric acid helps to suppress the interference of other metal ions or impurities in the raw material and reduce the influence of impurities on the extraction process.

[0015] The extractant used in the extraction process is a composite extractant, which applies a uniform mixture of modified ionic liquids, amide compounds and tributyl phosphate (TBP) to the extraction process. The strong negative charge of the carbonyl group is used to extract zirconium from the acidic chloride solution into the organic phase through the ion association mechanism, and a high-purity zirconium-containing solution is obtained through washing and stripping. The imidazolium cations in the extractant can coordinate with metal ions to form stable coordinated ions, which can reduce the volatility of the system; at the same time, the anions of the ionic liquid may also participate in the extraction process and combine with the zirconium ions through mechanisms such as electrostatic effects. The synergistic effect of these chemical reactions makes the imidazolium ionic liquids show higher efficiency and selectivity in the extraction of metallic zirconium.

[0016] TBP is a neutral extractant, and the oxygen atoms in its chemical structure can coordinate with metal zirconium atoms to form a neutral extractant. This coordination ability makes TBP have a certain affinity for metal ions. Imidazole ionic liquids have two parts: cations and anions. The cation part (imidazole cation) contains sites for coordination with metal ions, while the anion part binds to metal ions through mechanisms such as electrostatic interaction. The ionic liquid is modified by methyl stearate, and esters with long-chain alkyl structures are introduced into the imidazole ionic liquid, which can increase the polarity of the ionic liquid itself, improve stability, and reduce the wettability of the ionic liquid itself, thereby facilitating uniform mixing with TBP and amide compounds. At the same time, the introduction of long-chain alkyl enhances steric hindrance, which can enhance the hydrophobicity of the ionic liquid and the extractant as a whole, and help separate zirconium and hafnium during the extraction process. This complementarity in chemical structure enables them to act together on zirconium ions to form a more stable extraction complex, which combines the coordination ability of TBP and the electrostatic effect of imidazole ionic liquids, thereby improving the extraction efficiency of zirconium.

[0017] In addition, by adding imidazole ionic liquid to the extractant, the low viscosity and high solubility of the imidazole ionic liquid can be utilized to improve the fluidity of the extraction system, thereby improving the mass transfer efficiency during the extraction process and making the zirconium ions more likely to be extracted into the organic phase; at the same time, by adding amide compounds to the extractant, the amide compounds contain functional groups such as nitrogen atoms and oxygen atoms that can form coordination bonds with zirconium, and the coordination of these functional groups with TBP will produce a synergistic effect, thereby enhancing the extraction capacity of zirconium ions. In the present invention, TBP, amide compounds and ionic liquids can each provide different coordination sites to combine with zirconium ions to form a more stable extraction complex, and the synergistic effect of the multiple coordination sites can enhance the capture capacity of the extraction system for zirconium ions and jointly promote the extraction process.

[0018] Beneficial effects of the present invention: The invention realizes the separation of zirconium and hafnium by solvent extraction, and separates zirconium solution and hafnium solution by solution acidification, extraction with extractant, washing with sulfuric acid solution and back extraction. The method of the invention is simple, has good separation effect and high separation purity. DETAILED DESCRIPTION

[0019] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0020] In the following examples and comparative examples: The countercurrent chromatograph used was from Shanghai Tongtian Biotechnology Co., Ltd., model TSS-M10 (separation column capacity 10L); Zirconium oxychloride: purchased from Shanghai MacLean Biochemical Technology Co., Ltd., product number: Z888663; Allyl chloride: purchased from Shandong Nolai New Materials Co., Ltd.; Methylimidazole: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number: M109227; N, N, N', N'-Tetrabutylmalonamide: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number: N159450; Tributyl phosphate: purchased from Shanghai MacLean Biochemical Technology Co., Ltd., product number: T818517; N, N-dimethylbenzamide: purchased from Shanghai Titan Technology Co., Ltd., product number: RG69984; Zirconium tetrachloride: purchased from Shanghai MacLean Biochemical Technology Co., Ltd., product number: Z820722; N, N, N', N'-Tetramethyladipamide: purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd., product number: BD237979.

[0021] Example 1 The rotation speed of the countercurrent chromatograph in steps S3, S4 and S5 is 300 rpm.

[0022] S1. Add zirconium oxychloride to pure water, filter until the filtrate is clear and transparent after it is completely dissolved, then add concentrated hydrochloric acid to adjust the acidity of the aqueous phase, and stir to obtain an aqueous phase solution, so that the concentration of hydrochloric acid in the aqueous phase solution is 6 mol / L, and the concentration of zirconium ions in the aqueous phase solution is 20 g / L; S2. At 50°C, allyl chloride and methylimidazole in a molar ratio of 1.5:1 were refluxed by magnetic stirring for 8 hours, and the ionic liquid AMIMCl was obtained by distillation and rotary evaporation. AMIMCl was dissolved in ethyl acetate, and vinyl triethoxysilane was added after mixing evenly. After stirring evenly, methyl stearate was added and stirred evenly. After standing for 10 hours, it was heated to 55°C and stirred for 3 hours to obtain a modified ionic liquid, wherein the volume ratio of AMIMCl, ethyl acetate and vinyl triethoxysilane was 1:3:0.1; The modified ionic liquid, N,N,N',N'-tetrabutylmalonamide and tributyl phosphate in a volume ratio of 0.1:2:6 were fully mixed to obtain an extract, and then sulfonated kerosene was added to prepare an organic phase solution, wherein the volume ratio of the extract to the sulfonated kerosene was 1:3; S3, extracting by countercurrent chromatography, using the aqueous phase solution obtained in step S1 as the aqueous phase, and the organic phase solution obtained in step S2 as the organic phase, first filling the internal pipeline of the countercurrent chromatograph with the organic phase, and then injecting the organic phase and the aqueous phase simultaneously, during the simultaneous injection process, the volume ratio of the organic phase to the aqueous phase is 2:1, the temperature of the countercurrent chromatograph in the process is 30°C, the processing time is 30min, the zirconium in the aqueous phase is extracted into the organic phase to obtain an organic phase containing zirconium, and hafnium is retained in the aqueous phase, wherein the flow rate of the organic phase during the simultaneous injection process is 200 mL / min, and the flow rate of the aqueous phase is 100 mL / min; S4, washing the zirconium-containing organic phase with a 5 mol / L sulfuric acid solution as a detergent, first filling the internal pipeline of the countercurrent chromatograph with the detergent, and then injecting the detergent and the zirconium-containing organic phase simultaneously, with the detergent serving as the aqueous phase. During the simultaneous injection process, the ratio of the zirconium-containing organic phase to the detergent is 2:3, the treatment time is 30 min, the temperature of the countercurrent chromatograph is 25° C., and a zirconium-rich organic phase is obtained, wherein during the simultaneous injection process, the flow rate of the organic phase is 200 mL / min, and the flow rate of the aqueous phase is 300 mL / min; S5. Use pure water as the aqueous phase to back-extract the zirconium-rich organic phase. The ratio of pure water to the zirconium-rich organic phase is 5:1 to obtain a zirconium-containing solution. The temperature for back-extraction with pure water is 20°C and the time is 15 minutes. The flow rate of the zirconium-rich organic phase is 100 mL / min, and the flow rate of the aqueous phase is 500 mL / min.

[0023] Example 2 The rotation speed of the countercurrent chromatograph in steps S3, S4 and S5 is 350 rpm.

[0024] S1. Add zirconium oxychloride to pure water, filter until the filtrate is clear and transparent after it is completely dissolved, then add concentrated hydrochloric acid to adjust the acidity of the aqueous phase, and stir to obtain an aqueous phase solution, so that the concentration of hydrochloric acid in the aqueous phase solution is 7 mol / L, and the concentration of zirconium ions in the aqueous phase solution is 40 g / L; S2. At 53°C, allyl chloride and methylimidazole in a molar ratio of 1.5:1 were refluxed by magnetic stirring for 8-10 hours, and the ionic liquid AMIMCl was obtained by distillation and rotary evaporation. AMIMCl was dissolved in ethyl acetate, and vinyl triethoxysilane was added after mixing evenly. After stirring evenly, methyl stearate was added and stirred evenly. After standing for 11 hours, it was heated to 60°C and stirred for 4 hours to obtain a modified ionic liquid, wherein the volume ratio of AMIMCl, ethyl acetate and vinyl triethoxysilane was 1:4:0.12; The modified ionic liquid, N,N-dimethylbenzamide and tributyl phosphate in a volume ratio of 0.15:2:8 were fully mixed to obtain an extract, and then sulfonated kerosene was added to prepare an organic phase solution, wherein the volume ratio of the extract to the sulfonated kerosene was 2:4; S3, extracting by countercurrent chromatography, using the aqueous phase solution obtained in step S1 as the aqueous phase, and the organic phase solution obtained in step S2 as the organic phase, first filling the internal pipeline of the countercurrent chromatograph with the organic phase, and then injecting the organic phase and the aqueous phase simultaneously, wherein during the simultaneous injection process, the volume ratio of the organic phase to the aqueous phase is 2:1.8, the temperature of the countercurrent chromatograph during the process is 40°C, the processing time is 40min, the zirconium in the aqueous phase is extracted into the organic phase to obtain an organic phase containing zirconium, and hafnium is retained in the aqueous phase, wherein during the simultaneous injection process, the flow rate of the organic phase is 200 mL / min, and the flow rate of the aqueous phase is 180 mL / min; S4, using 5.5 mol / L sulfuric acid solution as a detergent to wash the zirconium-containing organic phase, first filling the internal pipeline of the countercurrent chromatograph with the detergent, and then injecting the detergent and the zirconium-containing organic phase simultaneously, with the detergent serving as the aqueous phase. During the simultaneous injection process, the ratio of the zirconium-containing organic phase to the detergent is 2:3.5, the treatment time is 40 min, the temperature of the countercurrent chromatograph is 35° C., and a zirconium-rich organic phase is obtained, wherein during the simultaneous injection process, the flow rate of the organic phase is 200 mL / min, and the flow rate of the aqueous phase is 350 mL / min; S5. Use pure water as the aqueous phase to back-extract the zirconium-rich organic phase. The ratio of pure water to the zirconium-rich organic phase is 5:1 to obtain a zirconium-containing solution. The back-extraction temperature with pure water is 30°C and the time is 20 minutes. The flow rate of the zirconium-rich organic phase is 100 mL / min, and the flow rate of the aqueous phase is 500 mL / min.

[0025] Example 3 The rotation speed of the countercurrent chromatograph in steps S3, S4 and S5 is 400 rpm.

[0026] S1. Add zirconium tetrachloride to pure water, filter until the filtrate is clear and transparent after it is completely dissolved, then add concentrated hydrochloric acid to adjust the acidity of the aqueous phase, and stir to obtain an aqueous phase solution, so that the concentration of hydrochloric acid in the aqueous phase solution is 8 mol / L, and the concentration of zirconium ions in the aqueous phase solution is 50 g / L; S2. At 55°C, allyl chloride and methylimidazole in a molar ratio of 1.5:1 were refluxed by magnetic stirring for 8-10 hours, and the ionic liquid AMIMCl was obtained by distillation and rotary evaporation. AMIMCl was dissolved in ethyl acetate, and vinyl triethoxysilane was added after mixing evenly. After stirring evenly, methyl stearate was added and stirred evenly. After standing for 12 hours, it was heated to 65°C and stirred for 5 hours to obtain a modified ionic liquid, wherein the volume ratio of AMIMCl, ethyl acetate and vinyl triethoxysilane was 1:5:0.15; The modified ionic liquid, N,N,N',N'-tetramethyl adipamide and tributyl phosphate in a volume ratio of 0.2:2:10 were fully mixed to obtain an extract, and then sulfonated kerosene was added to prepare an organic phase solution, wherein the volume ratio of the extract to the sulfonated kerosene was 3:5; S3, extracting by countercurrent chromatography, using the aqueous phase solution obtained in step S1 as the aqueous phase, and the organic phase solution obtained in step S2 as the organic phase, first filling the internal pipeline of the countercurrent chromatograph with the organic phase, and then injecting the organic phase and the aqueous phase simultaneously, wherein during the simultaneous injection process, the volume ratio of the organic phase to the aqueous phase is 2:2.5, the temperature of the countercurrent chromatograph during the process is 50°C, the processing time is 60min, the zirconium in the aqueous phase is extracted into the organic phase to obtain an organic phase containing zirconium, and hafnium is retained in the aqueous phase, wherein during the simultaneous injection process, the flow rate of the organic phase is 200 mL / min, and the flow rate of the aqueous phase is 250 mL / min; S4, using 6 mol / L sulfuric acid solution as a detergent to wash the zirconium-containing organic phase, first filling the internal pipeline of the countercurrent chromatograph with the detergent, and then injecting the detergent and the zirconium-containing organic phase simultaneously, with the detergent serving as the aqueous phase. During the simultaneous injection process, the ratio of the zirconium-containing organic phase to the detergent is 2:4, the treatment time is 50 min, the temperature of the countercurrent chromatograph is 45° C., and a zirconium-rich organic phase is obtained, wherein during the simultaneous injection process, the flow rate of the organic phase is 200 mL / min, and the flow rate of the aqueous phase is 400 mL / min; S5. Use pure water as the aqueous phase to back-extract the zirconium-rich organic phase. The ratio of pure water to the zirconium-rich organic phase is 5:1 to obtain a zirconium-containing solution. The back-extraction temperature with pure water is 40°C and the time is 30 minutes. The flow rate of the zirconium-rich organic phase is 100 mL / min, and the flow rate of the aqueous phase is 500 mL / min.

[0027] Example 4 The rotation speed of the countercurrent chromatograph in steps S3, S4 and S5 is 400 rpm.

[0028] S1. Add zirconium tetrachloride to pure water, filter until the filtrate is clear and transparent after it is completely dissolved, then add concentrated hydrochloric acid to adjust the acidity of the aqueous phase, and stir to obtain an aqueous phase solution, so that the concentration of hydrochloric acid in the aqueous phase solution is 8 mol / L, and the concentration of zirconium ions in the aqueous phase solution is 50 g / L; S2. At 55°C, allyl chloride and methylimidazole in a molar ratio of 1.5:1 were refluxed by magnetic stirring for 8-10 hours, and the ionic liquid AMIMCl was obtained by distillation and rotary evaporation. AMIMCl was dissolved in ethyl acetate, and vinyl triethoxysilane was added after mixing evenly. After stirring evenly, methyl stearate was added and stirred evenly. After standing for 11 hours, it was heated to 60°C and stirred for 5 hours to obtain a modified ionic liquid, wherein the volume ratio of AMIMCl, ethyl acetate and vinyl triethoxysilane was 1:4:0.15; The modified ionic liquid, N,N,N',N'-tetrabutylmalonamide and tributyl phosphate in a volume ratio of 0.2:2:10 were fully mixed to obtain an extract, and a diluent was added to prepare an organic phase solution, wherein the volume ratio of the extract to sulfonated kerosene was 3:5; S3, extracting by countercurrent chromatography, using the aqueous phase solution obtained in step S1 as the aqueous phase, and the organic phase solution obtained in step S2 as the organic phase, first filling the internal pipeline of the countercurrent chromatograph with the organic phase, and then injecting the organic phase and the aqueous phase simultaneously, wherein during the simultaneous injection process, the volume ratio of the organic phase to the aqueous phase is 2:2.5, the temperature of the countercurrent chromatograph during the process is 50°C, the time is 60min, the zirconium in the aqueous phase is extracted into the organic phase to obtain an organic phase containing zirconium, and hafnium is retained in the aqueous phase, wherein during the simultaneous injection process, the flow rate of the organic phase is 200 mL / min, and the flow rate of the aqueous phase is 250 mL / min; S4, washing the zirconium-containing organic phase with a 6 mol / L sulfuric acid solution as a detergent, first filling the internal pipeline of the countercurrent chromatograph with the detergent, and then injecting the detergent and the zirconium-containing organic phase simultaneously, with the detergent serving as the aqueous phase. During the simultaneous injection process, the ratio of the zirconium-containing organic phase to the detergent is 2:4, the treatment time is 50 min, the temperature of the countercurrent chromatograph is 45° C., and a zirconium-rich organic phase is obtained, wherein during the simultaneous injection process, the flow rate of the organic phase is 200 mL / min, and the flow rate of the aqueous phase is 400 mL / min; S5. Use pure water as the aqueous phase to back-extract the zirconium-rich organic phase. The ratio of pure water to the zirconium-rich organic phase is 5:1 to obtain a zirconium-containing solution. The back-extraction temperature with pure water is 40°C and the time is 30 minutes. The flow rate of the zirconium-rich organic phase is 100 mL / min, and the flow rate of the aqueous phase is 500 mL / min.

[0029] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in step S2 of Comparative Example 1, the ionic liquid is not subjected to modification treatment, and the other operations are the same.

[0030] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that in step S2 of Comparative Example 2, no ionic liquid is added, and the other operations are the same.

[0031] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that no amide compound is added in step S2 of Comparative Example 3, and the other operations are the same.

[0032] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the extractant in Comparative Example 4 is tributyl phosphate, and the other operations are the same.

[0033] Performance Test: Ammonia water was added to the zirconium-containing solutions obtained in Examples 1-4 and Comparative Examples 1-4 to make the solution pH 10, and the solution was stirred for 1.5 hours. After complete precipitation, the solution was filtered and dried at 120° C. for 13 hours to obtain a zirconium precipitate, which was calcined at 820° C. in an air atmosphere for 6 hours to obtain zirconium oxide. The purity of the zirconium oxide was measured according to the standard GB / T 23942-2009 "General Rules for Inductively Coupled Plasma Atomic Emission Spectrometry of Chemical Reagents". The results are shown in Table 1: Table 1

[0034] According to the above data, the extractant of the present invention has a good separation effect on zirconium and hafnium, and the hafnium content in the zirconium oxide prepared in Examples 1-4 is less than 0.0005%, which is much lower than the national standard (less than 0.01%). Therefore, the method of the present invention can obtain a zirconium solution with excellent separation effect and high purity.

[0035] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for separating zirconium and hafnium by solvent extraction, characterized in that: The following steps are involved: S1. Add zirconium oxychloride or zirconium tetrachloride into pure water, filter until the filtrate is clear and transparent after it is completely dissolved, then add concentrated hydrochloric acid to adjust the acidity of the aqueous phase, and stir to obtain an aqueous phase solution, so that the concentration of hydrochloric acid in the aqueous phase solution is 6-8 mol / L, and the concentration of zirconium ions in the aqueous phase solution is 20-50 g / L; S2. At 50-55°C, allyl chloride and methyl imidazole in a molar ratio of 1.5:1 were refluxed with magnetic stirring for 8-10 hours, and the ionic liquid 1-allyl-3-methylimidazolium chloride AMIMCl was obtained by distillation and rotary evaporation. AMIMCl was dissolved in ethyl acetate, and vinyl triethoxysilane was added after mixing evenly. After stirring evenly, methyl stearate was added and stirred evenly. After standing for 10-12 hours, it was heated to 55-65°C and stirred for 3-5 hours to obtain a modified ionic liquid, wherein the volume ratio of AMIMCl, ethyl acetate and vinyl triethoxysilane was 1: (3-5): (0.1-0.15); The modified ionic liquid, amide compound and tributyl phosphate in a volume ratio of (0.1-0.2):2:(6-10) are fully mixed to obtain an extract, and then a diluent is added to prepare an organic phase solution, wherein the volume ratio of the extract to the diluent is (1-3):(3-5); S3, extracting by countercurrent chromatography, using the aqueous phase solution obtained in step S1 as the aqueous phase, and the organic phase solution obtained in step S2 as the organic phase, first filling the internal pipeline of the countercurrent chromatography with the organic phase, and then injecting the organic phase and the aqueous phase simultaneously, wherein the volume ratio of the organic phase to the aqueous phase during the simultaneous injection process is 2: (1-2.5), extracting zirconium in the aqueous phase into the organic phase to obtain an organic phase containing zirconium, and leaving hafnium in the aqueous phase; S4, washing the zirconium-containing organic phase with a detergent, first filling the internal pipeline of the countercurrent chromatograph with the detergent, and then injecting the detergent and the zirconium-containing organic phase simultaneously, with the detergent serving as the aqueous phase. During the simultaneous injection process, the ratio of the zirconium-containing organic phase to the detergent is 2:(3-4), thereby obtaining a zirconium-rich organic phase; S5. Use pure water as the water phase to perform back extraction on the zirconium-rich organic phase, the ratio of pure water to the zirconium-rich organic phase is 5:1, and a zirconium-containing solution is obtained.

2. The method for separating zirconium and hafnium by solvent extraction according to claim 1, characterized in that: In step S2, the diluent is one of n-octane, sulfonated kerosene, toluene and a mixture of n-octane and n-octanol in a volume ratio of 9:

1.

3. The method for separating zirconium and hafnium by solvent extraction according to claim 1, characterized in that: In step S2, the amide compound includes one of N,N,N',N'-tetrabutylmalonamide, N,N-dimethylbenzamide, N,N,N,N-tetraalkylpyridinediamide and N-alkylcaprolactam.

4. The method for separating zirconium and hafnium by solvent extraction according to claim 1, characterized in that: In step S3, during the extraction, during the simultaneous injection of the organic phase and the aqueous phase, the temperature of the countercurrent chromatograph is 30-50°C, the processing time is 30-60min, the rotation speed of the countercurrent chromatograph is 300-400rpm, wherein the flow rate of the organic phase during the simultaneous injection process is 200 mL / min, and the flow rate of the aqueous phase is 100-250 mL / min.

5. The method for separating zirconium and hafnium by solvent extraction according to claim 1, characterized in that: In step S4, the detergent is a 5-6 mol / L sulfuric acid solution.

6. The method for separating zirconium and hafnium by solvent extraction according to claim 1, characterized in that: In step S4, during the simultaneous injection process, the temperature of the countercurrent chromatograph is 25-45°C, the processing time is 30-50 min, the rotation speed of the countercurrent chromatograph is 300-400 rpm, wherein during the simultaneous injection process, the flow rate of the organic phase is 200 mL / min, and the flow rate of the aqueous phase is 300-400 mL / min.

7. The method for separating zirconium and hafnium by solvent extraction according to claim 1, characterized in that: In step S5, the temperature for stripping with pure water is 20-40°C, the time is 15-30 min, the rotation speed of the countercurrent chromatograph is 300-400 rpm, the flow rate of the zirconium-rich organic phase is 100 mL / min, and the flow rate of the aqueous phase is 500 mL / min.

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