A method for directly separating trace metals from solid metal salts and its application

Abstract

The present invention discloses a method for directly separating trace metals from solid metal salts and its applications. The method includes steps such as the selection of matrix materials, the preparation of capture oil phases, the configuration of diffusion channel solutions, the Ostwald ripening process, the capture of target elements, and the separation and enrichment of target elements. By utilizing the principle that mass migration occurs in the form of ion diffusion during the Ostwald ripening process of crystals, the direct separation of trace metals from solid metal salts is achieved. This method is directly aimed at the extraction, recovery, and impurity removal of trace elements in solid crystal structures, with high separation efficiency and low energy consumption, and has broad application prospects in both the purification of solid metal salts and the extraction of trace elements.

Description

Technical Field

[0001] The invention relates to the technical field of separation and purification, in particular to a method for directly separating trace metals from solid metal salts and application thereof. Background Art

[0002] Some alkali metals (lithium, rubidium, cesium, etc.), rare earth elements (praseodymium, ytterbium, lutetium, etc.), precious metal elements (platinum, ruthenium, rhodium, gold, etc.), uranium, etc. have extremely important application positions in the fields of national defense, catalysis, energy storage, and medical treatment, and also have extremely high economic value. However, this type of mineral has obvious rare and scattered characteristics in distribution characteristics. It usually does not have a separate mineral and exists in the form of associated deposits, resulting in great challenges in enrichment, recovery, purification and separation of this type of elements. In the process of processing its associated minerals, most of this type of metal will enter other solid phases by forming a solid solution with the main product of mineral production, and will not be enriched in the production mother liquor. This mineral migration and enrichment law causes a large number of rare and high-value elements to suffer huge losses and economic losses with the use of the main product.

[0003] For example, salt lake brine contains rich Rb resources, which have important application value in the field of high-tech. At present, it has played an increasingly important role in high-tech fields such as new photovoltaic materials, quantum information storage, communications, and aerospace. However, no single Rb mine has been found so far, and more than 90% of the proven Rb resources are contained in seawater and salt lake brine. According to existing reports, the extremely low content of Rb in salt lake brine will be transported to the sea with potassium salt (KCl) and potassium carnallite (KMgCl3 .The crystals of 6H2O enter the solid phase in the form of a solid solution. According to sample detection, industrial-grade KCl produced from salt lake brine contains approximately 100 - 200 ppm of Rb. Through production process tracking, it is found that all the Rb in the salt lake brine ultimately exists in the form of a solid solution in the KCl product and does not accumulate in the mother liquor, which is contrary to the traditional cognitive theory but has not attracted wide attention. Based on the Rb content in industrial-grade KCl and China's planned production capacity of 1000 wt / year of KCl, the annual loss of Rb resources due to their occurrence in industrial-grade KCl will reach 2000 t, which is equivalent to 2850 t in terms of RbCl. Calculated at the current market price of 6000 yuan / kg, the economic value of the Rb resource loss caused by the production of industrial-grade KCl will reach 17.1 billion yuan per year. Therefore, it is extremely urgent to effectively recover Rb resources using industrial-grade KCl as the raw material. However, currently, the extraction of Rb can be divided into two categories based on different mineral types: the extraction of Rb from lepidolite-type solid minerals and the extraction of Rb from salt lake brine. There is little research focusing on the trace Rb in industrial-grade KCl and recovering it. If Rb is recovered from industrial-grade KCl by the method of dissolution and recrystallization, it will not only significantly increase the production cost of KCl, seriously affecting the normal production and supply of potash fertilizers, but also the extremely high K / Rb ratio will lead to a very low Rb recovery rate.

[0004] In addition, uranium and rare earth elements are associated with phosphate deposits and ultimately enter phosphate fertilizer products (products such as potassium dihydrogen phosphate and ammonium phosphate contain 100 ppm and above of U and various rare earth elements) during the production process of wet-process phosphoric acid, resulting in serious waste of U and rare earth elements; platinum group elements are associated with copper-nickel sulfide deposits and will also cause huge losses eventually with the production and use of copper and nickel. They have a very similar situation to Rb existing in the form of a solid solution in industrial-grade KCl. Additionally, during the utilization of some important materials, there are certain requirements for the purity of the products. The solid solution formed by trace elements and major elements makes it difficult to purify the materials. Especially when the trace elements are as low as the ppm level, it severely restricts the high-value utilization of the products. For example, it is difficult to remove magnesium and calcium from LiCl products; it is difficult to remove aluminum and rare earth separations with similar properties from rare earth elements.

[0005] Regarding the above common situations, if trace elements are recovered or removed before the production of the main product, the extremely complex matrix components, other impurity elements, and solution acidity will all lead to unsatisfactory recovery efficiency and recovery cost. If trace elements are recovered or removed by recrystallization after the production of the main product, it will face huge energy consumption, seriously affecting the market price and volume supply of the products.

[0006] In summary, there is an urgent need to explore a method that uses industrial-grade solid metal salts as the matrix material, which can not only directly achieve the effective recovery or removal of trace elements in the solid state, but also take into account the normal production of the matrix product or further improve its quality, so as to maximize the recovery and utilization of high-value elements or high-value products. Summary of the Invention

[0007] The object of the present invention is to provide a method for directly separating trace metals from solid metal salts in view of the technical defect of difficult separation of trace metals in solid metal salts in the prior art.

[0008] Another object of the present invention is to provide the application of the above method in the purification of solid metal salts.

[0009] Another object of the present invention is to provide the application of the above method in the extraction of trace elements.

[0010] The technical solution adopted to achieve the object of the present invention is as follows:

[0011] A method for directly separating trace metals from solid metal salts, comprising the following steps:

[0012] Step 1: Selection of matrix material

[0013] Select a water-soluble solid metal salt containing trace target metals as the matrix material; the particle size of the matrix material is less than 100 μm; preferably 1-50 μm.

[0014] Step 2: Preparation of capture oil phase

[0015] Mix the capture substance with the organic dispersion phase to obtain the capture oil phase; the capture substance is one of an extractant, an adsorbent, a displacing agent, and a precipitating agent; the organic dispersion phase is one or more of sulfonated kerosene, xylene, and cyclohexane.

[0016] Step 3: Preparation of diffusion channel solution

[0017] Dissolve the matrix material in water to prepare a diffusion channel solution, and adjust its pH value; the saturation of the diffusion channel solution is 50-80%, preferably 60-80%.

[0018] Step 4: Ostwald ripening process and target element capture

[0019] Add the matrix material selected in Step 1 to the capture oil phase prepared in Step 2, and add the diffusion channel solution obtained in Step 3; the matrix material undergoes Ostwald ripening, and the trace target metals released during the process diffuse into the capture oil phase through the diffusion channel solution; the capture substance captures the trace target metals;

[0020] Step 5: Target element separation and enrichment

[0021] The purified solid metal salt is obtained by separating, washing, and drying the parent material after the Ostwald ripening in Step 4.

[0022] Separate trace target metals from the capture substance.

[0023] In the above technical solution, when the capture substance is an extractant, in Step 5, the oil phase after separating the parent material is back-extracted with an aqueous back-extraction agent to obtain an aqueous phase containing trace target metals, and the trace target metal compound is obtained by concentration and crystallization; the oil phase obtained by back-extracting with the aqueous back-extraction agent is used as the capture oil phase and reapplied to Step 4; Steps 4-5 are cyclically executed.

[0024] When the capture substance is an adsorbent, in Step 5, the capture substance is screened, and the trace target metal compound is obtained after elution and concentration.

[0025] When the capture substance is a displacement agent, in Step 5, the displacement agent is obtained by screening and further the trace target metal compound is obtained by displacement, washing, and concentration.

[0026] When the capture substance is a precipitant, in Step 5, the target metal compound is directly obtained by screening.

[0027] In the above technical solution, in Step 4, 2-10 g of the parent material is dispersed in 30-150 mL of the capture oil phase and continuously stirred at a rate of 100-2000 rpm, and the parent material is completely dispersed in the oil phase; the parent material is preferably 2-5 g; the capture oil phase is preferably 30-100 mL.

[0028] In Step 4, the solid-liquid mass ratio of the parent material to the diffusion channel solution is (1-5):1; the feeding rate of the diffusion channel solution is 1-10 g / s, preferably 1-5 g / s, and continuously stirred for 1-24 h, preferably 1-10 h.

[0029] In the above technical solution, the parent material includes one of industrial-grade KCl, industrial-grade KH2PO4, industrial-grade LiCl, and industrial-grade PrCl3.

[0030] The trace target metals include one of Rb, Ca, Mg, Al, U, and rare earth elements, or a mixture of U and rare earth elements.

[0031] On the other hand of the present invention, the application of the above method in the purification of solid metal salts.

[0032] On the other hand of the present invention, the application of the above method in the extraction of trace elements.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] 1. The method for directly separating trace metals from solid metal salts provided by the present invention is based on the principle that the Ostwald ripening process of crystals in oil-in-water emulsions will promote the phenomenon of mass migration of crystals in the form of ion diffusion, thereby achieving the effective release of trace target elements in the crystal structure, and intercepting and capturing the target elements by other substances. The overall process is equivalent to multiple recrystallization processes of crystals, thereby achieving the purpose of extracting, recycling and removing impurities of trace components in solid crystal structures. In the field of separation and purification, a new method for directly extracting, recycling and removing impurities of trace elements in solid unit cell structures is provided.

[0035] 2. The method for separating trace metals from solid metal salts provided by the present invention can directly realize the recovery or removal of trace elements contained in industrial-grade solid metal salts, without the need to redissolve the industrial-grade products in liquids for recovery or removal, and thus has obvious advantages in reducing energy consumption and reducing purification costs. In addition, the technology of the present invention greatly expands the contact interface between the water and oil phases by constructing a liquid membrane ion transmission channel, which is more conducive to the transfer of target ions from the water phase to the oil phase, thereby improving the purification efficiency.

[0036] 3. The method for separating trace metals from solid metal salts provided by the present invention has a core principle that the crystals will undergo mass migration in the form of ion diffusion during the Ostwald ripening process. The mass migration behavior in the form of ion diffusion will further reconstruct the crystal structure, thereby achieving the effective release of the target ions stored in the solid solution crystal structure, and effectively intercepting and capturing the target ions during the ion migration process, and finally achieving the recovery or removal of the target ions. It is important that the Ostwald ripening phenomenon is common in various types of crystal growth and processing processes, especially in oil-in-water emulsions or colloids. Therefore, as long as the crystals can undergo the Ostwald ripening process in the oil-in-water emulsion, the recovery or removal of the trace elements therein can be achieved by screening suitable solvents and capture agents. This technical invention also provides a relatively broad and representative application example, which fully proves the universality of the technical invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A technical roadmap for methods of separating trace metals from solid metal salts;

[0038] Figure 2 Shown are SEM images of industrial grade KCl before and after separation of rubidium in Example 1;

[0039] Figure 3 Shown are SEM images of industrial-grade potassium dihydrogen phosphate before and after separation of U and rare earth elements in Example 2. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] Example 1

[0042] A method for directly separating trace metals from solid metal salts, comprising the following steps:

[0043] Step 1: Selection of matrix material

[0044] Select a water-soluble solid metal salt containing trace target metal as the matrix material;

[0045] Step 2: Preparation of capture oil phase

[0046] Mix the capture substance with the organic dispersion phase to obtain the capture oil phase;

[0047] Step 3: Preparation of diffusion channel solution

[0048] Dissolve the matrix material in water to prepare a diffusion channel solution, and adjust its pH value;

[0049] Step 4: Ostwald ripening process and target element capture

[0050] Add the matrix material selected in Step 1 to the capture oil phase prepared in Step 2, and add the diffusion channel solution obtained in Step 3; the matrix material undergoes Ostwald ripening, and the trace target metal released during the process diffuses through the diffusion channel solution into the capture oil phase; the capture substance captures the trace target metal;

[0051] Step 5: Target element separation and enrichment

[0052] Separate, wash, and dry the matrix material after Ostwald ripening in Step 4 to obtain purified solid metal salt;

[0053] Separate the trace target metal from the capture substance.

[0054] The principle of the above method is that the Ostwald ripening process of the matrix material crystals in the water-in-oil emulsion promotes the mass transfer of the crystals in the form of ion diffusion. This phenomenon realizes the effective release of trace target elements in the crystal structure, and other substances are used to intercept and capture the target elements. The overall process is equivalent to multiple recrystallization processes of the crystals, so as to achieve the purposes of extracting, recycling, and removing impurities of trace components in the solid crystal structure.

[0055] Example 2

[0056] Recovery of trace Rb in industrial-grade KCl

[0057] Comprising the following steps:

[0058] (1) Preparation of industrial-grade KCl: Using low-sodium carnallite from salt lakes as raw material, 10 g of industrial-grade KCl with a particle size of about 5 μm was prepared by the cold decomposition crystallization method as the parent material. Through ICP-MS detection, it contains about 150 ppm of Rb.

[0059] (2) Preparation of the capture oil phase: 4-tert-butyl-2-(α-methylbenzyl)phenol was dissolved in sulfonated kerosene to prepare a capture oil phase with a concentration of 1.0 mol / L.

[0060] (3) Preparation of the diffusion channel solution: At room temperature, the industrial-grade KCl prepared in step (1) was dissolved in water to prepare a solution with a saturation of 80%, and the pH value of this solution was adjusted to 12 - 14.

[0061] (4) Rb + Capture: The industrial-grade KCl prepared in step (1) was dispersed in 60 mL of the capture oil phase prepared in step 2, and continuously stirred at a stirring rate of 700 rpm. After the industrial-grade KCl was completely dispersed in the oil phase, 3 g of the diffusion channel solution prepared in step (3) was added to the oil phase at a feeding rate of 3 g / s, and continuously stirred in this state for 1 - 3 h.

[0062] (5) Rb + Separation and enrichment: After step (4) was completed, the mixture was subjected to solid-liquid separation. The separated solid phase was further washed with ethanol and dried to obtain industrial-grade KCl after recovering Rb; the separated sulfonated kerosene was back-extracted with a 1 mol / L HCl aqueous solution to obtain an RbCl solution, and further evaporated to obtain an RbCl product.

[0063] (6) Recycling of the oil phase: The sulfonated kerosene after back-extraction in step (5) was reapplied to step 4 to recover Rb in the next batch of raw materials.

[0064] Appendix Figure 2 Figure 25 shows the SEM images of the industrial-grade KCl before and after purification in Example 1. It can be seen that the particle size of the purified KCl has increased significantly, indicating an obvious Ostwald ripening process. Through ICP-MS detection, the Rb content in the purified KCl is reduced to less than 20 ppm, the recovery rate of Rb reaches about 92%, and the loss rate of KCl is about 5%.

[0065] Example 3

[0066] Recovery of trace U and rare earth elements in industrial-grade KH2PO4

[0067] (1) Preparation of industrial-grade KH2PO4: Using phosphate rock as raw material, 10 g of industrial-grade KH2PO4 with a particle size of about 2 - 10 μm was prepared as the matrix material through the wet-process phosphoric acid method. Through ICP-MS detection, it contains about 100 ppm of U, about 90 ppm of Yb, and about 90 ppm of Tm.

[0068] (2) Preparation of the oil phase: Bis(2-ethylhexyl) phosphinic acid was dissolved in cyclohexane to prepare a capture oil phase with a concentration of 0.8 mol / L.

[0069] (3) Preparation of the diffusion channel solution: At room temperature, the industrial-grade KH2PO4 prepared in step (1) was dissolved in water to prepare a solution with a saturation of 80%, and the pH value of the solution was adjusted to 4.

[0070] (4) Ostwald ripening process and target element capture: The industrial-grade KH2PO4 prepared in step (1) was dispersed in 30 mL of the extraction oil phase prepared in step 2, and continuously stirred at a stirring rate of 800 rpm. After the industrial-grade KH2PO4 was completely dispersed in the oil phase, 3 - 5 g of the diffusion channel solution prepared in step (3) was added to the oil phase at a feeding rate of 1 - 5 g / s, and continuously stirred in this state for 3 - 5 h.

[0071] (5) Separation and enrichment of target elements: After step (4) was completed, the mixture was subjected to solid-liquid separation. The separated solid phase was washed with ethanol and dried to obtain industrial-grade KH2PO4 after recovering U, Yb, and Tm; the separated liquid phase was back-extracted with a 1 mol / L HCl aqueous solution to obtain a solution containing U, Yb, and Tm, and further evaporated to obtain U, Yb, and Tm chloride products.

[0072] (6) Recycling of the oil phase: The cyclohexane oil phase after back-extraction in step (5) was reapplied to step 4 to recover U, Yb, and Tm in the next batch of raw materials.

[0073] Appendix Figure 3 Figure 21 is the SEM image of industrial-grade KH2PO4 before and after purification in Example 2. It can be seen that the particle size of the purified KH2PO4 has increased significantly, indicating an obvious Ostwald ripening process. Through ICP-MS detection, the contents of U, Yb, and Tm in the purified KH2PO4 are reduced to less than 10 ppm, and the recovery rates of U, Yb, and Tm reach about 95%, 93%, and 93% respectively, and the loss rate of KH2PO4 is almost 0.

[0074] Example 4

[0075] Removal of trace amounts of Ca and Mg in industrial-grade LiCl

[0076] (1) Preparation of industrial-grade LiCl: Using salt lake brine as raw material, 10 g of industrial-grade LiCl containing crystal water with a particle size of about 5 - 10 μm was prepared by the adsorption-membrane coupling method as the parent material. Through ICP-MS detection, it contains about 200 ppm of Ca and Mg.

[0077] (2) Preparation of the oil phase: Bis(2-ethylhexyl) phosphinic acid was dissolved in sulfonated kerosene to prepare a capture oil phase with a concentration of 0.8 mol / L.

[0078] (3) Preparation of the diffusion channel solution: At room temperature, the industrial-grade LiCl containing crystal water prepared in step (1) was dissolved in water to prepare a solution with a saturation of 80%, and the pH value of the solution was adjusted to 4.

[0079] (4) Ostwald ripening process and target element capture: The industrial-grade LiCl containing crystal water prepared in step (1) was dispersed in 30 mL of the extraction oil phase prepared in step 2, and continuously stirred at a stirring rate of 800 rpm. After the industrial-grade KCl was completely dispersed in the oil phase, 3 g of the diffusion channel solution prepared in step (3) was added to the oil phase at a feeding rate of 2 g / s, and continuously stirred in this state for 5 h.

[0080] (5) Separation and enrichment of target elements: After step (4) was completed, the mixture was subjected to solid-liquid separation, and the separated solid phase was washed with toluene, dried, and dehydrated to obtain LiCl with Ca and Mg removed.

[0081] (6) Recycling of the oil phase: The sulfonated kerosene oil phase separated in step (5) was back-extracted with a 1 mol / L HCl aqueous solution to remove Ca and Mg, and then reapplied to step 4 to remove Ca and Mg in the next batch of raw materials.

[0082] Through ICP-MS detection, it was obtained that the contents of Ca and Mg in the treated LiCl were reduced to less than 10 ppm, and the removal rates of Ca and Mg reached about 94% and 93% respectively, and the loss rate of LiCl was almost 0.

[0083] Example 5

[0084] Removal of trace Al in industrial-grade PrCl3

[0085] (1) Preparation of industrial-grade PrCl3: Using phosphate rock as raw material, PrCl3 solution was enriched during the wet-process phosphoric acid production process, and 10 g of industrial-grade PrCl3 particles containing crystal water with a particle size of about 5 - 10 μm was prepared as the parent material. Through ICP-MS detection, it contains about 300 ppm of Al.

[0086] (2) Preparation of the oil phase: Dissolve 4-octyloxybenzoic acid in sulfonated kerosene to prepare a capture oil phase with a concentration of 0.5 mol / L.

[0087] (3) Preparation of the diffusion channel solution: Dissolve the industrial-grade PrCl3 prepared in step (1) in water at room temperature to prepare a solution with a saturation of 60%, and adjust the pH value of the solution to 3.

[0088] (4) Ostwald ripening process and target element capture: Disperse the industrial-grade PrCl3 containing crystal water prepared in step (1) in 30 mL of the extraction oil phase prepared in step 2, and continuously stir at a stirring rate of 1000 rpm. After the PrCl3 is completely dispersed in the oil phase, add 3 g of the diffusion channel solution prepared in step (3) to the oil phase at a feeding rate of 1 g / s, and continuously stir in this state for 4 h.

[0089] (5) Separation and enrichment of target elements: After step (4) is completed, perform solid-liquid separation on the mixture. The separated solid phase is then washed with toluene and dried to obtain PrCl3 containing crystal water after removing Al.

[0090] (6) Recycling of the oil phase: The sulfonated kerosene separated in step (5) is back-extracted with a 1 mol / L HCl aqueous solution to remove Al, and then reapplied to step 4 to remove Al from the next batch of raw materials.

[0091] It was detected by ICP-MS that the Al content in the treated PrCl3 was reduced to about 50 ppm, and the removal rate of Al reached about 75%. However, the loss rate of PrCl3 reached about 45%. The main reason for the high raw material loss rate is that 4-octyloxybenzoic acid 3+ has an extraction effect on Pr, and the loss rate can be further reduced by optimizing the type of extractant.

[0092] Example 6

[0093] Removal of Trace Mg in Industrial-Grade KCl

[0094] It includes the following steps:

[0095] (1) Preparation of industrial-grade KCl: Use low-sodium carnallite from salt lakes as raw materials, and prepare 10 g of industrial-grade KCl with a particle size of about 5 μm as the matrix material by the cold decomposition crystallization method. It contains about 0.18% of Mg detected by ICP-MS.

[0096] (2) Preparation of the capture oil phase: Disperse potassium hydroxide in sulfonated kerosene to prepare 60 mL of a capture oil phase with a concentration of 1.0 mol / L;

[0097] (3) Diffusion channel solution preparation: Dissolve the industrial-grade KCl prepared in step (1) in water to prepare a solution with a saturation of 80% at room temperature, and adjust the pH value of the solution to 13.

[0098] (4) Mg 2+ Capture: Disperse the industrial-grade KCl prepared in step (1) in 60 mL of the capture oil phase prepared in step 2, and continuously stir at a stirring rate of 800 rpm. After the industrial-grade KCl is completely dispersed in the oil phase, add 3 g of the diffusion channel solution prepared in step (3) to the oil phase at a feeding rate of 3 g / s, and continuously stir for 1 - 3 h in this state. During this process, Mg 2+ combines with OH- to form Mg(OH)2 precipitate.

[0099] (5) Separation of Mg: After step (4) is completed, perform solid-liquid separation on the mixture. The separated solid phase is screened using a 200-mesh sieve. The small crystals below the sieve are Mg(OH)2, and the material above the sieve is the KCl matrix material.

[0100] (6) Recycling of the oil phase: Reapply the sulfonated kerosene in step (5) to step 4 to remove Mg from the next batch of raw materials.

[0101] It is detected by ICP-MS that the Mg content in the treated KCl is reduced to about 100 ppm, the removal rate of Mg reaches about 99.7%, and the loss rate of KCl is almost about 5%.

[0102] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for directly separating trace metals from solid metal salts, characterized in that: It includes the following steps: Step 1: Selection of matrix material Select a water-soluble solid metal salt containing trace target metal as the matrix material; Step 2: Preparation of capture oil phase Mix the capture substance with the organic dispersion phase to obtain the capture oil phase; Step 3: Preparation of diffusion channel solution Dissolve the matrix material in water to prepare a diffusion channel solution and adjust its pH value; Step 4: Ostwald ripening process and target element capture Add the matrix material selected in Step 1 to the capture oil phase prepared in Step 2, and add the diffusion channel solution obtained in Step 3; the matrix material undergoes Ostwald ripening, and the trace target metal released during the process diffuses through the diffusion channel solution into the capture oil phase; the capture substance captures the trace target metal; Step 5: Separation and enrichment of target element Separate, wash, and dry the matrix material after Ostwald ripening in Step 4 to obtain a purified solid metal salt; Separate the trace target metal from the capture substance.

2. The method according to claim 1, characterized in that: In Step 1, the particle size of the matrix material is less than 100 μm.

3. The method according to claim 1, characterized in that: The particle size of the matrix material is 1 - 50 μm.

4. The method according to claim 1, characterized in that: In Step 2, the capture substance is one of an extractant, an adsorbent, a displacement agent, and a precipitant; The organic dispersion phase is one or several of sulfonated kerosene, xylene, and cyclohexane.

5. The method according to claim 4, characterized in that: When the capture substance is an extractant, in Step 5, back-extract the oil phase after separating the matrix material with an aqueous back-extractant to obtain an aqueous phase containing trace target metal, and concentrate and crystallize to obtain a trace target metal compound; When the capture substance is an adsorbent, in Step 5, screen the capture substance, elute and concentrate to obtain a trace target metal compound; When the capture substance is a displacement agent, in Step 5, obtain the displacement agent by screening, and further obtain a trace target metal compound through back-displacement, washing, and concentration; When the capture substance is a precipitant, in Step 5, directly obtain the target metal compound by screening.

6. The method according to claim 5, wherein: When the capture substance is an extractant, in Step 5, the oil phase obtained by back-extracting with an aqueous back-extractant is used as the capture oil phase and reapplied to Step 4; Steps 4 - Step 5 are cyclically executed.

7. The method according to claim 1, characterized in that: In Step 3, the saturation of the diffusion channel solution is 50 - 80%.

8. The method according to claim 1, characterized in that: In Step 3, the saturation of the diffusion channel solution is 60 - 80%.

9. The method according to claim 1, wherein: In Step 4, disperse 2 - 10 g of the matrix material in 30 - 150 mL of the capture oil phase, and continuously stir at a rate of 100 - 2000 rpm until the matrix material is completely dispersed in the oil phase.

10. The method according to claim 1, wherein: In Step 4, the matrix material is 2 - 5 g.

11. The method according to claim 1, wherein: In Step 4, the capture oil phase is 30 - 100 mL.

12. The method according to claim 7, characterized in that: In Step 4, the solid-liquid mass ratio of the matrix material to the diffusion channel solution is (1 - 5):1; The feeding rate of the diffusion channel solution is 1 - 10 g / s, and continuously stir for 1 - 24 h.

13. The method according to claim 7, wherein: In Step 4, the feeding rate of the diffusion channel solution is 1 - 5 g / s.

14. The method according to claim 7, characterized in that: In Step 4, continuously stir for 1 - 10 h.

15. Application of the method according to any one of claims 1 - 14 in the purification of solid metal salts.

16. Application of the method according to any one of claims 1 - 14 in the extraction of trace elements.

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