Method for extracting and separating zirconium and hafnium from mixed solution containing zirconium and hafnium

Abstract

The invention discloses a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, which overcomes the defects that various complexing agents or coordination agents such as thiocyanate radicals, fluorinions and the like which increase the impurity removal burden of the subsequent process and greatly pollute the environment need to be introduced in order to efficiently extract and separate zirconium and hafnium in the past. The acidity of the feed liquid is controlled, the polymerization trend, degree and occurrence form of zirconium and hafnium in the solution are changed, the property difference of zirconium and hafnium in the same environment is enlarged, extraction of hafnium is rapidly inhibited, and effective separation of hafnium and zirconium is achieved. According to the method, the single-stage zirconium extraction rate can reach 80% or above, the hafnium co-extraction rate is low, the separation coefficient is high, the separation effect is good, a commercial extraction agent is used, the cost is low, the process is green, environmental pollution is small, industrialization is easy to achieve, and the method is particularly suitable for separating zirconium and hafnium from feed liquid with the high zirconium and hafnium content.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium. Background Art

[0002] Zirconium and hafnium are strategic key metals that have long played an important role in the nuclear industry and are key materials for building nuclear reactors. Zirconium has a very low thermal neutron absorption cross section (0.18×10 -28 m 2 ), as the structural material and cladding material of uranium fuel elements in nuclear reactors, it can effectively avoid the absorption and waste of thermal neutrons and ensure the efficient conduct of nuclear reactions. Hafnium has a larger thermal neutron capture cross section (1.2×10 -22 cm 2 ), which exhibits nuclear properties that are completely opposite to zirconium, and is mainly used as a control material for nuclear reactors. Therefore, zirconium and hafnium must be separated in advance to reach nuclear grade (or atomic energy level) before they can be used in the nuclear industry, that is, the mass content of hafnium Hf in zirconium Zr is required to be less than 0.01%, and the mass content of zirconium Zr in hafnium Hf is required to be less than 2%.

[0003] As a clean energy with mature technology, nuclear power has a strong revival trend and is developing at a faster pace. Therefore, the demand for nuclear-grade zirconium and hafnium is growing both at home and abroad. However, due to the contraction of the lanthanide series, the atomic radius and ionic radius of zirconium and hafnium are similar, and their physical and chemical properties are very similar. Therefore, in nature, the two do not exist alone in the ore, but coexist in isomorphic symbiosis. Zirconium often contains 1% to 3% hafnium by mass. In the process of extraction and metallurgy, the two are inseparable and it is very difficult to separate them. The efficient separation of zirconium and hafnium is the key technology for the preparation of nuclear-grade zirconium and hafnium materials.

[0004] In order to effectively separate zirconium and hafnium, domestic and foreign researchers have carried out a lot of research work on the separation technology of the two since the 1950s, and have proposed different methods, including solvent extraction, step-by-step crystallization, exchange resin ion adsorption, etc. Among them, solvent extraction is widely used in the production of nuclear-grade zirconium and hafnium because of its advantages of simple equipment, low cost, large production volume, adaptability to complex systems, and ease of automation. At present, there are dozens of extraction systems proposed for zirconium and hafnium separation, such as neutral phosphorus-containing extraction systems represented by tributyl phosphate (TBP) and triphenylphosphine oxide (TOPO), neutral oxygen-containing extraction systems represented by methyl isobutyl ketone (MIBK), and neutral nitrogen-containing extraction systems represented by trioctylamine (such as TOA / Alamine300 / N235, etc.). Among them, MIBK-HSCN+HCl, TBP-HCl-HNO3, and TOA / N235-H2SO4 have been widely used in industry.

[0005] The main principle of solvent extraction is to use the different degrees of hydrolysis, polymerization and depolymerization of zirconium and hafnium in the solution, and then use the difference in the distribution behavior of the formed complex species in the two phases to achieve the separation of the two. In the previous solvent extraction separation of zirconium and hafnium, in order to "amplify" the difference in the properties of similar elements zirconium and hafnium, it is often necessary to add various complexing agents or coordination agents such as thiocyanate and fluoride ions to the mixed solution containing zirconium and hafnium, which will increase the burden of impurity removal in the subsequent process and cause greater environmental pollution. In order to increase the reaction difference, it is often necessary to introduce specific complexing (coordinating) agents (ions). For example, extraction systems represented by methyl isobutyl ketone (MIBK) and diisobutyl ketone (DIBK) all require the use of thiocyanate (or thiocyanate HSCN); CN108118150A discloses a method for preferentially extracting hafnium and separating zirconium hafnium using a synergistic extraction system composed of DIBK and phosphonic acid extractants, but ammonium salts are required, and the extraction process is relatively complicated; CN117566791A discloses a method for preferentially extracting hafnium with an acidic phosphorus extractant to achieve zirconium and hafnium separation, but fluoride ions (or hydrofluoric acid, fluoride salts) need to be introduced. Although these specific complexing agents improve the efficiency of zirconium and hafnium separation, they increase the impurity removal and environmental burden of subsequent processes. For example, the MIBK method for separating zirconium and hafnium, which accounts for nearly 2 / 3 of the global nuclear-grade zirconium and hafnium production, is easily decomposed into hydrogen sulfide, methyl mercaptan and CN under acidic conditions. - and other toxic decomposition products, polluting the environment. Therefore, research on efficient and green (SCN-free - 、F - The solvent extraction system with addition of other additives is still a hot topic in the field of zirconium and hafnium separation. Summary of the invention

[0006] The object of the present invention is to provide a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium in view of the above-mentioned deficiencies in the prior art, thereby changing the polymerization trend, degree and occurrence form of zirconium and hafnium in the mixed solution containing zirconium and hafnium, amplifying the difference in properties between the two under the same environment, rapidly suppressing the extraction of hafnium, and controlling the extraction rate of zirconium to change slightly, thereby achieving effective separation of the two.

[0007] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: The present invention provides a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, comprising the following steps: S1. The extractant and the diluent are mixed to prepare an organic phase for extraction; S2. The hydrogen peroxide, acid and zirconium-hafnium aqueous solution containing zirconium ions and hafnium ions are mixed, and the concentration of the acid and the molar ratio of the total amount of hydrogen peroxide and zirconium-hafnium are controlled; S3. The organic phase and the zirconium-hafnium aqueous phase liquid are mixed in a certain volume ratio, and then shaken, allowed to stand, and separated at a certain temperature to obtain a loaded organic phase and a raffinate aqueous phase, respectively; S4. The loaded organic phase and the stripping agent are mixed in a volume ratio of 1:1, and the mixture is shaken, allowed to stand, and separated into phases at room temperature for stripping.

[0008] Preferably, the diluent is one or more of kerosene, sulfonated kerosene, aviation oil, D80 solvent oil, D60 solvent oil and benzene; Preferably, the extractant is an amine or quaternary ammonium salt extractant, the amine extractant is one or more of trioctylamine, triisooctylamine and trioctylamine, specifically trioctylamine (TOA, Alamine300, N235), triisooctylamine (TEHA) and trioctylamine (Alamine336, Alamine308), and the quaternary ammonium salt extractant is methyl trioctyl ammonium chloride (Aliquat336); Preferably, the concentration of the extractant in the organic phase formed by the extractant and the diluent is 0.001-1 mol / L.

[0009] Preferably, the total concentration of zirconium and hafnium in the zirconium and hafnium aqueous phase solution is 0.001-1 mol / L, and the concentration of hafnium is no more than half of the concentration of zirconium.

[0010] Preferably, in step S2, the total acid concentration is controlled to be not less than 0.5 mol / L; preferably, the total acid concentration is controlled to be 0.5-11 mol / L; more preferably, the total acid concentration is controlled to be 7-11 mol / L.

[0011] Preferably, the acid in step S2 is any one or more of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, perchloric acid, chloric acid, hypochlorous acid and phosphoric acid.

[0012] Preferably, the molar amount of hydrogen peroxide in step S2 is 0.1 to 5 times the total molar amount of zirconium and hafnium in the zirconium and hafnium aqueous phase feed solution; more preferably, the molar amount of hydrogen peroxide is 0.1 to 3.1 times the total molar amount of zirconium and hafnium in the zirconium and hafnium aqueous phase feed solution.

[0013] Preferably, the volume ratio of the organic phase to the zirconium-hafnium aqueous phase is 1:2-5:1; and / or the extraction and shaking are performed at 10-30° C. for 5-40 min.

[0014] Preferably, the stripping agent is water or an acidic solution, the acidic solution is any one or two of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, hypochlorous acid and chloric acid, and the concentration of the acidic solution is 0.5-8 mol / L.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium of the present invention changes the polymerization trend, degree and occurrence form of zirconium and hafnium in the mixed solution containing zirconium and hafnium by adding hydrogen peroxide to the mixed solution containing zirconium and hafnium and adjusting and controlling the acidity of the mixed solution containing zirconium and hafnium, amplifies the difference in properties between the two under the same environment, and rapidly suppresses the extraction of hafnium, while the extraction rate of zirconium remains almost unchanged. The characteristics of hydrogen peroxide and the peroxide ion clusters formed by complexation can also partially alleviate the third phase generated during the extraction process. At the same time, the third phase can be dissolved and eliminated by the stripping agent during stripping, and the process is reversible with the extraction process, thereby achieving effective separation of the two. The present invention solves the problems of the prior art that various complexing agents or coordination agents such as thiocyanate and fluoride ion, which increase the burden of impurity removal in subsequent processes and cause greater environmental pollution, need to be added to efficiently extract and separate zirconium and hafnium. The single-stage zirconium extraction of the present invention can reach more than 80%, the co-extraction of hafnium is low, the separation coefficient is high (currently up to 257.3), the separation effect is good, the cost is low, the process is green, the environmental pollution is small, and it is easy to realize industrialization. It is particularly suitable for separating zirconium and hafnium from a mixed solution with high zirconium and hafnium contents.

[0016] The above is an overview of the technical solution of the invention. The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the relationship diagram of the effect of the total concentration of zirconium and hafnium on the extraction separation coefficient when no hydrogen peroxide is added; Figure 2 This is a relationship diagram showing the effect of the amount of hydrogen peroxide on the extraction rate of zirconium and hafnium and the corresponding separation coefficient when the total concentration of zirconium and hafnium is 0.006 mol / L; Figure 3 This is a relationship diagram showing the effect of hydrogen peroxide dosage on the extraction rate of zirconium and hafnium and the corresponding separation coefficient when the total concentration of zirconium and hafnium is 0.035 mol / L. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following is a detailed description in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] The present invention mainly conducts a systematic and in-depth study on the problems existing in the direct extraction and separation of zirconium and hafnium in a zirconium-hafnium mixed solution. Any method for separating similar elements of zirconium and hafnium is based on the difference in the properties of zirconium and hafnium in the environment in which they are located. However, zirconium and hafnium itself are highly oxygen-affinity elements and will undergo hydrolysis and polymerization in an aqueous solution to form various oxygen-containing polynuclear ion clusters, resulting in an extremely complex composition of the zirconium and hafnium aqueous solution. Therefore, it is difficult to separate zirconium and hafnium in a zirconium-hafnium mixed solution.

[0020] Generally speaking, the polymerization tendency of zirconium is greater than that of hafnium. As the content of zirconium and hafnium in the aqueous solution decreases or the acidity of the solution increases, the polymerization of the two will be inhibited to a certain extent. At the same time, when the solution contains SCN - 、F - 、SO4 2- , Cl - , ClO - 、ClO4 - 、NO3 - When there are anions, there will be competition coordination with hydroxide ions, resulting in certain differences in the polymerization direction of zirconium and hafnium. For example, there have been reports of the separation of zirconium and hafnium in a hydrochloric acid system using amine extractants (TEHA, Alamine300, Alamine308, etc.), and the separation coefficient can reach 300 when the extractant concentration is 1 mol / L. However, this extraction system is only applicable to the case of very low zirconium and hafnium concentrations, such as zirconium concentrations of about 0.002 mol / L and hafnium concentrations of about 0.001 mol / L. Once the zirconium and hafnium concentrations increase, the separation coefficient drops sharply, from the original 42.2 to 14.3 (see Figure 1 The influence of the total concentration of zirconium and hafnium on the extraction separation coefficient when no hydrogen peroxide is added) is shown in the figure. At the same time, a large amount of flocculent precipitation is produced to form a third phase, and the separation effect is very poor. This may be because as the total concentration of zirconium and hafnium increases, the degree of polymerization of the two increases, which may form a "twin baby" form or the chemical properties of the ion clusters are not obviously different, resulting in a significant reduction in the separation effect.

[0021] The present invention adds hydrogen peroxide to the mixed solution containing zirconium and hafnium, especially for the mixed solution system with high zirconium and hafnium concentration, so that the third phase is alleviated to a certain extent during the extraction process, and the separation coefficient is increased from 14.3 without adding hydrogen peroxide to 257.3 with adding hydrogen peroxide. This may be because hydrogen peroxide can provide more oxygen, and at the same time, various oxygen acid radicals formed by the partial reaction of peroxide and hydrogen peroxide with inorganic acid are complexed with zirconium and hafnium, which alleviates the polymerization degree of zirconium and hafnium and changes the polymerization trend, so that the difference in the polymerization properties of zirconium and hafnium in the mixed solution containing zirconium and hafnium is sharply expanded. Moreover, with the addition of hydrogen peroxide, the extraction of hafnium is rapidly suppressed, from 90% without adding hydrogen peroxide to less than 10% after adding hydrogen peroxide, while the extraction rate of zirconium is slightly reduced, so that the separation coefficient is rapidly increased (see Figure 2 , Figure 3 The relationship diagram of the effect of hydrogen peroxide dosage on the extraction rate of zirconium and hafnium and the corresponding separation coefficient when the total concentration of zirconium and hafnium is 0.006 mol / L and 0.035 mol / L respectively).

[0022] The present invention changes the polymerization trend, degree of polymerization and occurrence form of zirconium and hafnium in the zirconium and hafnium mixed solution through the addition of hydrogen peroxide and other complete technical solutions, amplifies the difference in properties between the two under the same environment, rapidly suppresses the extraction of hafnium, and controls the extraction rate of zirconium to change slightly, thereby achieving effective separation of the two. At the same time, the characteristics of hydrogen peroxide and the peroxide ion clusters formed by complexation can also partially alleviate the third phase generated during the extraction process. During stripping, the third phase can be dissolved and eliminated by the stripping agent, and the process is reversible with the extraction process, which not only generates new extraction behavior and extraction mechanism, but also generates unexpected excellent extraction effect.

[0023] The invention can well realize the extraction and separation of zirconium and hafnium by adding hydrogen peroxide and adjusting and controlling the total acid concentration in the zirconium and hafnium liquid system, and provides a new extraction and separation method which is simple, low-cost and easy to realize for the zirconium and hafnium leaching liquid of industrial nuclear waste and zirconium and hafnium ore.

[0024] The specific implementation of the present invention is a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, comprising the following steps: S1. Prepare an organic phase: Mix the extractant and the diluent to prepare an organic phase for extraction; S2. preparing a zirconium-hafnium aqueous solution: adding hydrogen peroxide and acid to the zirconium-hafnium aqueous solution containing zirconium ions and hafnium ions and controlling the concentration of the acid and the molar ratio of the total amount of hydrogen peroxide to the zirconium-hafnium amount; exemplarily preparing a zirconium-hafnium aqueous solution containing zirconium ions and hafnium ions with zirconium oxychloride octahydrate and hafnium oxychloride octahydrate.

[0025] S3. The organic phase and the zirconium-hafnium aqueous phase liquid are mixed in a certain volume ratio, and then shaken, allowed to stand, and separated at a certain temperature to obtain a loaded organic phase and a raffinate aqueous phase, respectively; S4. The loaded organic phase and the stripping agent are mixed in a volume ratio of 1:1, and the mixture is shaken, allowed to stand, and separated into phases at room temperature for stripping.

[0026] As an example of an embodiment, in step S1, the diluent may be one or more of kerosene, sulfonated kerosene, aviation oil, D80 solvent oil, D60 solvent oil and benzene; the extractant may be one or more of methyl trioctyl ammonium chloride, trioctylamine, triisooctylamine and trioctylamine, specifically trioctylamine (TOA, Alamine300, N235), methyl trioctyl ammonium chloride (Aliquat336), triisooctylamine (TEHA) and trioctylamine (Alamine336, Alamine308); the extractant concentration in the organic phase formed by the extractant and the diluent is 0.001 mol / L~1 mol / L, such as 0.001, 0.005, 0.03, 0.09, 0.3, 0.5, 0.7, 1 mol / L. The exemplary preferred extractant concentration is 0.005~0.3 mol / L.

[0027] As an example of an embodiment, in step S2, the total concentration of zirconium and hafnium in the zirconium and hafnium aqueous phase liquid is 0.001-1 mol / L, such as 0.001, 0.005, 0.03, 0.09, 0.3, 0.5, 0.7, 1 mol / L, and the concentration of hafnium does not exceed half of the zirconium concentration. The exemplary preferred zirconium ion concentration is 0.004-0.032 mol / L, and the hafnium ion concentration is 0.0016 mol / L, that is, the total concentration of zirconium and hafnium is 0.005-0.035 mol / L. The total acid concentration is controlled to be not less than 0.5 mol / L; preferably, the total acid concentration is controlled to be 0.5 mol / L-11 mol / L; more preferably, the total acid concentration is 7 mol / L-11 mol / L, and the exemplary preferred total acid concentration is 8-10 mol / L if the acid is hydrochloric acid. In step S2, the acid is any one or more of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, perchloric acid, chloric acid, hypochlorous acid and phosphoric acid. The molar amount of hydrogen peroxide is 0.1 to 5 times the total molar amount of zirconium and hafnium in the zirconium and hafnium aqueous phase feed solution. For example, the molar amount of hydrogen peroxide is 0.5 to 3 times the total molar amount of zirconium and hafnium in the zirconium and hafnium aqueous phase feed solution, and specifically, it can be 0.1, 0.5, 1, 2, 3, 4, 5; preferably, the molar amount of hydrogen peroxide is 0.1 to 3.1 times the total molar amount of zirconium and hafnium in the zirconium and hafnium aqueous phase feed solution.

[0028] As an example of an embodiment, in step S3, the volume ratio of the organic phase to the zirconium-hafnium aqueous phase liquid is 1:2-5:1, and the exemplary preferred volume ratio of the organic phase to the zirconium-hafnium aqueous phase liquid is 1:1-3:1, and specifically can be 1:2, 1:1, 2:1, 3:1, 4:1, 5:1; and / or the extraction is shaken at 10-30°C for 5-40 min, and specifically can be shaken at 10, 25, 30°C for 5, 20, 30, 40 min.

[0029] As an example of an embodiment, in step S4, the stripping agent is water or an acidic solution, the acidic solution is any one or two of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, hypochlorous acid and chloric acid, and the concentration of the acidic solution is 0.5~8mol / L, such as 0.5, 0.9, 2, 4, 6, 8mol / L, and the concentration of an exemplary preferred acidic solution such as a sulfuric acid solution is 2mol / L.

[0030] These embodiments are merely exemplary expressions of the scheme of the present invention, and do not exhaustively list the dosage of the substance, the substance itself, and the method. At the same time, the following method is used for testing and verification: the test method is to determine the concentration of hafnium ions and zirconium ions in the residual water phase of step S3 by ICP-MS, and then calculate the concentration of hafnium ions and zirconium ions in the organic phase by subtraction method, and calculate the distribution ratio of zirconium and hafnium, the separation coefficient of zirconium and hafnium, and the extraction rate of zirconium and hafnium in turn; and the concentration of hafnium ions and zirconium ions in the stripping water phase of step S4 is determined by ICP-MS, and the stripping rate of zirconium and hafnium is calculated in turn.

[0031] Example 1

[0032] This embodiment provides a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, comprising the following steps: (1) Preparation of organic phase: The extractant and diluent kerosene are mixed to prepare the organic phase for extraction, and the extractant is Aliquat 336 (methyl trioctyl ammonium chloride), and the concentration of the extractant is 0.005 mol / L.

[0033] (2) preparing a zirconium-hafnium aqueous solution: using zirconium oxychloride octahydrate and hafnium oxychloride octahydrate as raw materials, preparing a zirconium-hafnium aqueous solution with a zirconium ion concentration of 0.004 mol / L and a hafnium ion concentration of 0.0016 mol / L; adding hydrogen peroxide and an acid to the zirconium-hafnium aqueous solution and controlling the acid concentration (hydrochloric acid is exemplarily selected as the acid) to 10 mol / L; the molar amount of hydrogen peroxide is twice the total molar amount of zirconium and hafnium in the zirconium-hafnium aqueous solution; and simultaneously preparing a zirconium-hafnium aqueous solution without adding hydrogen peroxide under the same conditions.

[0034] (3) shaking the organic phase and the zirconium-hafnium aqueous phase feed solution at a volume ratio of 3:1 at 25° C. for 30 min, letting it stand, and separating the phases to obtain a loaded organic phase and a raffinate aqueous phase, respectively; (4) The loaded organic phase and the stripping agent (the stripping agent is exemplarily a sulfuric acid solution with a concentration of 2 mol / L) in step (3) are shaken, allowed to stand, and separated at room temperature in a volume ratio of 1:1 to perform stripping.

[0035] The concentrations of hafnium ions and zirconium ions in the raffinate water phase of step S3 are determined by ICP-MS, and then the concentrations of hafnium ions and zirconium ions in the organic phase are calculated by subtraction, and the distribution ratio of zirconium and hafnium, the separation coefficient of zirconium and hafnium, and the extraction rates of zirconium and hafnium are calculated in turn; and the concentrations of hafnium ions and zirconium ions in the stripping water phase of step S4 are determined by ICP-MS, and the stripping rates of zirconium and hafnium are calculated in turn. The test results show that the system without hydrogen peroxide has an extraction rate of 99% for zirconium, an extraction rate of 80% for hafnium, and a separation coefficient of 37.75; while the system with hydrogen peroxide has an extraction rate of 97% for zirconium, an extraction rate of 26% for hafnium, and a separation coefficient of 101.56. After stripping, the stripping rates of zirconium and hafnium are 67% and 70%, respectively.

[0036] Example 2

[0037] This embodiment provides a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, which is basically the same as that of embodiment 1, except that: (1) Preparation of organic phase: The extractant and diluent kerosene are mixed to prepare the organic phase for extraction, and the extractant is Aliquat 336 (methyl trioctyl ammonium chloride), and the concentration of the extractant is 0.008 mol / L.

[0038] Preparation of zirconium and hafnium aqueous solution: The concentration of zirconium ions is 0.006 mol / L and the concentration of hafnium ions is 0.0016 mol / L.

[0039] The test results show that the system without hydrogen peroxide has an extraction rate of 99% for zirconium, 92% for hafnium, and a separation factor of 51.3; while the system with hydrogen peroxide has an extraction rate of 95% for zirconium, 16% for hafnium, and a separation factor of 98.1.

[0040] Example 3

[0041] This embodiment provides a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, which is basically the same as that of embodiment 1, except that: (1) Preparation of organic phase: The extractant and diluent kerosene are mixed to prepare the organic phase for extraction, and the extractant is Aliquat 336 (methyl trioctyl ammonium chloride), and the concentration of the extractant is 0.0022 mol / L.

[0042] (2) Preparation of zirconium and hafnium aqueous phase feed solution: The zirconium ion concentration is 0.032 mol / L; the hafnium ion concentration is 0.0016 mol / L; the molar amount of hydrogen peroxide is 0.5 times the total molar amount of zirconium and hafnium in the zirconium and hafnium aqueous phase feed solution.

[0043] The test results show that the system without hydrogen peroxide has an extraction rate of 99% for zirconium, an extraction rate of 94% for hafnium, and a separation factor of 29.4, while the system with hydrogen peroxide has an extraction rate of 99% for zirconium, an extraction rate of 51% for hafnium, and a separation factor of 257.3.

[0044] Example 4

[0045] This embodiment provides a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, which is basically the same as that of embodiment 3, except that: (2) The molar amount of hydrogen peroxide is 1 times the total molar amount of zirconium and hafnium in the zirconium and hafnium aqueous phase solution.

[0046] The test results show that the extraction rate of zirconium and hafnium in the system with hydrogen peroxide added is 82%, 10% and the separation coefficient is 42.4.

[0047] Example 5

[0048] This embodiment provides a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, which is basically the same as that of embodiment 1, except that: (1) Preparation of organic phase: The extractant and diluent kerosene are mixed to prepare the organic phase for extraction, and the extractant is triisooctylamine such as TEHA (2-ethyl-N,N-bis(2-ethylhexyl)-1-hexylamine), and the concentration of the extractant is 0.3 mol / L.

[0049] (2) Preparation of zirconium-hafnium aqueous solution: Add hydrogen peroxide and acid into the zirconium-hafnium aqueous solution and control the acid concentration (hydrochloric acid is used as an example) to 9 mol / L.

[0050] (3) shaking, standing, and phase separation of the organic phase and the zirconium-hafnium aqueous phase feed liquid in sequence at a volume ratio of 1:1 at 25° C. to obtain a loaded organic phase and a raffinate aqueous phase, respectively; The test results show that the system without hydrogen peroxide has an extraction rate of 99% for zirconium, an extraction rate of 94% for hafnium, and a separation factor of 10.4, while the system with hydrogen peroxide has an extraction rate of 98% for zirconium, an extraction rate of 73% for hafnium, and a separation factor of 20.6.

[0051] Example 6

[0052] This embodiment provides a method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, which is basically the same as that of embodiment 5, except that: (1) Preparation of organic phase: The extractant and diluent kerosene are mixed to prepare the organic phase for extraction. The extractant is triisooctylamine such as Alamine 300, and the concentration of the extractant is 0.1 mol / L.

[0053] (2) Preparation of zirconium-hafnium aqueous solution: Add hydrogen peroxide and acid into the zirconium-hafnium aqueous solution and control the acid concentration (hydrochloric acid is used as an example) to 8 mol / L.

[0054] The test results show that the system without hydrogen peroxide has an extraction rate of 97% for zirconium, 39% for hafnium, and a separation factor of 63.0, while the system with hydrogen peroxide has an extraction rate of 65% for zirconium, 1% for hafnium, and a separation factor of 185.1.

[0055] Based on the above embodiments and in combination with the attached Figure 2 , Figure 3 It can be seen that in the entire extraction system, the extraction rate of zirconium and hafnium will decrease with the increase of hydrogen peroxide dosage, but hafnium always decreases faster, which causes the extraction separation coefficient of the two to increase rapidly first and then decrease; at the same time, the range of the optimal molar ratio of hydrogen peroxide to the total amount of zirconium and hafnium for the extraction separation effect will also change with the change of the total amount of zirconium and hafnium. In the actual extraction and separation process, the amount of hydrogen peroxide should be adjusted according to the specific purpose by comprehensively considering the acidity of the feed liquid and the total concentration of zirconium and hafnium.

[0056] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the invention should also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium, characterized in that: The following steps are involved: S1. The extractant and the diluent are mixed to prepare an organic phase for extraction; S2. The hydrogen peroxide, acid and zirconium-hafnium aqueous solution containing zirconium ions and hafnium ions are mixed, and the concentration of the acid and the molar ratio of the total amount of hydrogen peroxide and zirconium-hafnium are controlled; S3. The organic phase and the zirconium-hafnium aqueous phase liquid are mixed in a certain volume ratio, and then shaken, allowed to stand, and separated at a certain temperature to obtain a loaded organic phase and a raffinate aqueous phase, respectively; S4. The loaded organic phase and the stripping agent are mixed in a volume ratio of 1:1, and the mixture is shaken, allowed to stand, and separated into phases at room temperature for stripping.

2. The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium according to claim 1, characterized in that: The diluent is any one or more of kerosene, sulfonated kerosene, aviation oil, D80 solvent oil, D60 solvent oil and benzene.

3. The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium according to claim 1, characterized in that: The extractant is an amine or quaternary ammonium salt extractant.

4. The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium according to claim 1, characterized in that: The concentration of the extractant in the organic phase formed by the extractant and the diluent is 0.001-1 mol / L.

5. The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium according to claim 1, characterized in that: The total concentration of zirconium and hafnium in the zirconium and hafnium aqueous phase liquid is 0.001-1 mol / L, and the concentration of hafnium is no more than half of the concentration of zirconium.

6. The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium according to claim 1, characterized in that: In the step S2, the total acid concentration is controlled to be not less than 0.5 mol / L; preferably, the total acid concentration is controlled to be 0.5-11 mol / L; more preferably, the total acid concentration is 7-11 mol / L.

7. The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium according to claim 1, characterized in that: The acid in step S2 is any one or more of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, perchloric acid, chloric acid, hypochlorous acid and phosphoric acid.

8. The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium according to claim 1, characterized in that: The molar amount of hydrogen peroxide in step S2 is 0.1 to 5 times the total molar amount of zirconium and hafnium in the zirconium and hafnium aqueous phase feed solution; more preferably, the molar amount of hydrogen peroxide is 0.1 to 3.1 times the total molar amount of zirconium and hafnium in the zirconium and hafnium aqueous phase feed solution.

9. The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium according to claim 1, characterized in that: The volume ratio of the organic phase to the zirconium-hafnium aqueous phase is 1:2-5:1; and / or, the extraction is shaken at 10-30° C. for 5-40 minutes.

10. The method for extracting and separating zirconium and hafnium from a mixed solution containing zirconium and hafnium according to claim 1, characterized in that: The stripping agent is water or an acidic solution, the acidic solution is any one or two of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, hypochlorous acid and chloric acid, and the concentration of the acidic solution is 0.5-8 mol / L.

Images