A method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction

Abstract

This invention belongs to the field of high-purity inorganic material preparation technology, and relates to a method for preparing ultra-high-purity lead fluoride from lead oxide based on supercritical complexation extraction. Using lead oxide as raw material, lead acetate is synthesized through acetylation, deep purification through SCC-CO2 supercritical complexation extraction, and fluorination precipitation to prepare 5N-grade ultra-high-purity lead fluoride. Lead acetate is a strongly polar ionic organic salt with high lattice energy, and it is almost insoluble and does not leak in the SCC-CO2 system. Cu, which is present as an associated component in the raw material... 2+ Fe 3+ Zn 2+ Cd 2+ Bi 3+ Impurity metal ions, under the action of a complexing agent, form weakly polar, fat-soluble metal complexes, which are then efficiently extracted by supercritical CO2 and continuously carried out of the system, achieving deep separation of lead acetate from impurities. The purified ultra-high purity lead acetate reacts with ultra-high purity hydrofluoric acid to directly produce 5N grade ultra-high purity lead fluoride with a purity ≥99.995%. This method is suitable for industrial production due to its simple process, environmental friendliness, high impurity removal depth, and stable preparation of ultra-high purity lead fluoride.

Description

Technical Field

[0001] This invention belongs to the field of high-purity inorganic material preparation technology, specifically relating to a method for preparing ultra-high-purity lead fluoride from lead oxide based on supercritical complexation extraction. Background Technology

[0002] Ultra-high purity lead fluoride is a key basic material for scintillation crystals, infrared optical windows, and nuclear radiation detection devices. It requires stringent control over heavy metal impurity content, with individual impurities typically needing to be below 1 ppm and a purity exceeding 99.995%. Traditional preparation processes use industrial lead oxide as the starting material, involving dissolution in acetic acid, multiple recrystallizations from aqueous solutions, and fluorination precipitation to obtain lead fluoride. These methods suffer from problems such as long process times, large wastewater volumes, difficulty in deeply removing impurities like Cu, Fe, Zn, Cd, and Bi, and the potential for secondary pollution, making it difficult to consistently meet the requirements for 5N-grade ultra-high purity materials.

[0003] Supercritical CO2 complexation extraction (SCC-CO2) combines the advantages of high mass transfer efficiency, environmental friendliness, and strong selectivity of complexation reactions with those of supercritical fluids, enabling efficient separation of heavy metal impurities in anhydrous and organic solvent-free systems. A key challenge is how to achieve the separation of lead acetate from trace heavy metal impurities using SCC-CO2 technology, providing a simple, environmentally friendly, and highly effective method for industrial production, capable of achieving high impurity removal and stable preparation of 5N grade ultra-high purity lead fluoride. Summary of the Invention

[0004] Based on this, the purpose of this invention is to provide a method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction. This method can separate lead acetate from trace heavy metal impurities through SCC-CO2 technology, and is suitable for industrial production. The process is simple, environmentally friendly, has a high degree of impurity removal, and can stably prepare 5N grade ultra-high purity lead fluoride.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction, comprising the following steps: S1, Acetic acidification to synthesize crude lead acetate: Lead oxide is added to an acetic acid solution, heated to react, and the insoluble matter is filtered to obtain a crude lead acetate solution; the crude lead acetate solution is concentrated under reduced pressure to obtain crude lead acetate solid; S2, Supercritical complex extraction and purification: The crude lead acetate solid described in S1 is mixed with the complexing agent and then loaded into a supercritical extraction vessel. CO2 is introduced to the supercritical state, and dynamic or static supercritical complex extraction is performed to obtain ultra-high purity lead acetate. S3, Preparation of ultra-high purity lead fluoride: Electronic grade hydrofluoric acid is added to the solution of ultra-high purity lead acetate described in S2, and the reaction yields lead fluoride precipitate; the lead fluoride precipitate is aged, filtered, washed and dried to obtain 5N grade ultra-high purity lead fluoride product.

[0006] Further, the mass concentration of the acetic acid solution in S1 is 14~16%, the acetic acid is high-purity acetic acid (purity > 99.99%), the molar ratio of lead oxide to acetic acid in the acetic acid solution is 1:(4~5), and the lead oxide is industrial lead oxide.

[0007] Furthermore, the heating reaction in S1 is carried out at a temperature of 60~80℃ for 1~3h; the crude lead acetate solution is concentrated under reduced pressure at a vacuum of -0.085~-0.09Mpa and a temperature of 45~60℃ for 8~20h to obtain anhydrous lead acetate powder, which is white.

[0008] Further, the amount of complexing agent added in S2 is 0.8~1.5% of the mass of the solid lead acetate; the complexing agent includes any one or more of diethyldithiocarbamate (DDTC), di(2-ethylhexyl) phosphate (D2EHPA, abbreviated as P204), trioctylphosphine oxide (TOPO) and 2-ethylhexylphosphonate mono-2-ethylhexyl ester (P507).

[0009] Furthermore, the supercritical complex extraction step described in S2 includes: S21, turn on the SCC-CO2 extraction system, set the extraction pressure to 20~30MPa, the extraction temperature to 40~60℃, introduce CO2, keep the extraction temperature and pressure constant, and perform static extraction for 25~35min; S22, open the CO2 inlet and outlet valves to continuously feed supercritical CO2 fluid into the supercritical extraction vessel at a CO2 flow rate of 10±0.5 L / min. Maintain dynamic extraction for 1.4~1.6 h to carry out impurity complexes out of the system. The total extraction time is 2 h. S23, stop CO2 feeding, close the inlet and outlet valves, keep the extraction reactor sealed, stop heating, wait for the extraction reactor to drop to 25±5℃, open the pressure relief valve, first reduce the pressure to 9~10MPa, then continue to depressurize to atmospheric pressure, open the extraction reactor, collect the solid material from the reactor, and you will get ultra-high purity lead acetate.

[0010] Furthermore, the content of Cu, Fe, Zn, Cd, and Bi in the ultra-high purity lead acetate is ≤1 ppm, and the main content of lead acetate is ≥99.995%.

[0011] Furthermore, the concentration of the ultra-high purity lead acetate solution in S3 is 0.1~0.3 mol / L, and the solvent used for the ultra-high purity lead acetate solution is deionized water.

[0012] Furthermore, the mass concentration of the electronic-grade hydrofluoric acid in S3 is 30-50%; the electronic-grade hydrofluoric acid is added dropwise to the ultra-high purity lead acetate solution at 20-40°C under stirring conditions, and the amount of electronic-grade hydrofluoric acid added is 1-1.2 times the theoretical amount.

[0013] Furthermore, the aging time in S3 is 40-80 minutes, the washing is done with high-purity water (Grade I water as specified in GB / T6682-2008 "Specifications and Test Methods for Water Used in Analytical Laboratories") until neutral, and the drying is vacuum drying at a temperature of 100-110°C for 6-10 hours.

[0014] The purity of the 5N grade ultra-high purity lead fluoride product prepared by the above preparation method in this invention is >99.995%.

[0015] The beneficial effects of this invention are: This invention provides a method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complex extraction. Supercritical CO2 is used as the non-polar extraction medium, exhibiting extremely low solubility for strongly polar, ionic compounds. Lead acetate, a strongly polar ionic organic salt with high lattice energy, is almost insoluble and does not leak in the SCC-CO2 system, remaining stably in the extraction vessel as a solid phase. Cu, which is present as an adjunct in the raw material... 2+ Fe 3+ Zn 2+ Cd 2+ Bi 3+ Impurity metal ions, under the action of a complexing agent, form weakly polar, fat-soluble metal complexes, which can be efficiently extracted by supercritical CO2 and continuously carried out of the system, achieving deep separation of lead acetate from impurities. Ultra-high purity lead acetate purified by SCC-CO2 reacts with ultra-high purity hydrofluoric acid to directly produce 5N grade ultra-high purity lead fluoride with a purity ≥99.995%. This method is suitable for industrial production due to its simple process, environmental friendliness, high impurity removal depth, and stable preparation of 5N grade ultra-high purity lead fluoride. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. All mentioned embodiments are implemented based on the technical solutions of the present invention, and detailed implementation processes are given. However, it should be stated that the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available reagents and materials; and unless otherwise specified, the room temperature or room temperature refers to 25±5℃.

[0017] Example 1

[0018] A method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction, comprising the following steps: (1) Acetic acidification to synthesize crude lead acetate: Add 8 L of 15% high-purity acetic acid solution to the reaction vessel, start stirring and heating, slowly add 1000 g of industrial lead oxide, raise the temperature to 70 ℃ and stir for 2 h until the solution is clear and transparent, stop heating and stirring, wait for the temperature to drop below 40 ℃, filter the impurities to obtain crude lead acetate solution, concentrate under reduced pressure to obtain crude lead acetate solid.

[0019] (2) Supercritical complex extraction purification: Take 1000 g of crude lead acetate, add 12 g of DDTC complexing agent, mix evenly, and then load into a supercritical extraction vessel for supercritical complex extraction: Start the SCC-CO2 extraction system: pressure 25 MPa, temperature 50 ℃, introduce CO2, maintain extraction temperature and pressure constant, and let stand for half an hour; open the CO2 inlet and outlet valves to continuously introduce supercritical CO2 fluid into the extraction vessel at a CO2 flow rate of 10 L / min, maintain dynamic extraction for 1.5 h to remove impurity complexes from the system, with a total extraction time of 2 h; stop the CO2 feed, close the inlet and outlet valves, keep the extraction reactor sealed, stop heating, and wait for the extraction vessel to cool to room temperature. Slowly open the pressure relief valve to reduce the pressure to 10 MPa first, and then continue to slowly depressurize to atmospheric pressure. Throughout the process, pay attention to the depressurization rate and prevent material splashing and loss. After the pressure has completely dropped to atmospheric pressure and the temperature has dropped to room temperature, open the extraction vessel and collect the solid material from the vessel. This material is ultra-high purity lead acetate. ICP testing shows that Cu, Fe, Zn, Cd, and Bi are all ≤1 ppm, and the main content of lead acetate is ≥99.995%.

[0020] (3) Preparation of ultra-high purity lead fluoride: Purified lead acetate was prepared into a 0.2 mol / L aqueous solution. 1.05 times the theoretical amount of 40% electronic grade HF was slowly added dropwise under stirring at room temperature. The mixture was aged for 60 min, the solid was separated by filtration, and the solid was washed with high-purity water until neutral. It was then vacuum dried at 105 ℃ for 8 h to obtain ultra-high purity lead fluoride. The results of ICP testing of this ultra-high purity lead fluoride are shown in Table 1 below.

[0021] Table 1 Summary of ICP test results for ultra-high purity lead fluoride prepared in Example 1

[0022] As can be seen from Table 1, the lead fluoride prepared in Example 1 has a purity of ≥99.999% and a single metal impurity of ≤0.916 ppm.

[0023] Example 2 A method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction, comprising the following steps: (1) Acetic acidification to synthesize crude lead acetate: The lead oxide acetylation steps are the same as in Example 1.

[0024] (2) Supercritical complex extraction purification: Add 20g of DDTC complexing agent, SCC-CO2 extraction conditions: pressure 28 MPa, temperature 55 ℃, extraction time 1.5 h.

[0025] (3) Preparation of ultra-high purity lead fluoride: The fluorination, washing and drying processes are the same as in Example 1. The results of ICP detection of the ultra-high purity lead fluoride are shown in Table 2 below.

[0026] Table 2 Summary of ICP test results for ultra-high purity lead fluoride prepared in Example 2

[0027] As can be seen from Table 2, the lead fluoride prepared in Example 2 has a purity of ≥99.999% and a single metal impurity of ≤0.790 ppm.

[0028] Example 3 A method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction, comprising the following steps: (1) Acetic acidification to synthesize crude lead acetate: Take 1000 g of industrial lead oxide, add 8 L of 15 wt% high-purity acetic acid solution, react at 70 ℃ for 2 h, filter, concentrate and dry to obtain crude lead acetate.

[0029] (2) Supercritical complex extraction purification: Take 1000 g of crude lead acetate, add 10 g of complexing agent D2EHPA, mix evenly and load into a supercritical extraction vessel for supercritical complex extraction: Start the SCC-CO2 extraction system: pressure 25 MPa, temperature 50 ℃, CO2 flow rate 10 L / min, static extraction for 0.5 h, dynamic extraction for 1.5 h, then depressurize to obtain ultra-high purity lead acetate.

[0030] (3) Preparation of ultra-high purity lead fluoride: Purified lead acetate was prepared into a 0.2 mol / L aqueous solution. 1.1 times the theoretical amount of 40% electronic grade HF was slowly added dropwise under stirring at room temperature. The mixture was aged for 60 min, the solid was separated by filtration, and the solid was washed with high-purity water until neutral. The solid was then vacuum dried at 105 ℃ for 8 h to obtain ultra-high purity lead fluoride. The results of ICP testing of this ultra-high purity lead fluoride are shown in Table 3 below.

[0031] Table 3 Summary of ICP test results for ultra-high purity lead fluoride prepared in Example 3

[0032] As can be seen from Table 3, the lead fluoride prepared in Example 3 has a purity of ≥99.9991% and a single metal impurity of ≤0.659ppm.

[0033] Example 4 (1) Acetic acidification to synthesize crude lead acetate: The lead oxide acetylation steps are the same as in Example 1.

[0034] (2) Supercritical complex extraction purification: Add 8 g of complexing agent trioctylphosphine oxide (TOPO) and mix thoroughly with crude lead acetate. Extraction conditions: 28 MPa, 55 ℃, CO2 flow rate 10 L / min, time 1.5 h. After purification, the purity of lead acetate is ≥99.995%, and all impurities are ≤1 ppm.

[0035] (3) The preparation of ultra-high purity lead fluoride was the same as in Example 1. The results of ICP testing of the ultra-high purity lead fluoride are shown in Table 4 below.

[0036] Table 4 Summary of ICP test results for ultra-high purity lead fluoride prepared in Example 4

[0037] As can be seen from Table 4, the lead fluoride prepared in Example 4 has a purity of ≥99.998% and a single metal impurity of ≤0.889 ppm.

[0038] Example 5 (1) Acetic acidification to synthesize crude lead acetate is the same as in Example 1.

[0039] (2) Supercritical complex extraction purification: 12 g of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507) was added. Extraction conditions: 26 MPa, 52 ℃, CO2 flow rate 10 L / min, time 2 h, Cu, Fe, Zn, Cd and Bi were deeply removed, and 5N grade lead acetate was produced; (3) The preparation of ultra-high purity lead fluoride was the same as in Example 1. The results of ICP testing of the ultra-high purity lead fluoride are shown in Table 5 below.

[0040] Table 5 Summary of ICP test results for ultra-high purity lead fluoride prepared in Example 5

[0041] As can be seen from Table 5, the lead fluoride prepared in Example 5 has a purity of ≥99.9992% and a single metal impurity of ≤0.957ppm.

[0042] Example 6 (1) Acetic acidification to synthesize crude lead acetate is the same as in Example 1.

[0043] (2) Supercritical complex extraction purification: Add 6 g of DDTC + 4 g of TOPO and use in combination. Extraction conditions: 25 MPa, 50 ℃, CO2 flow rate 12 L / min, time 1.5 h, to obtain lead acetate with a single impurity content of less than 0.6 ppm and a main content ≥ 99.998%.

[0044] (3) Preparation of ultra-high purity lead fluoride: Purified lead acetate was prepared into a 0.2 mol / L aqueous solution. 1.1 times the theoretical amount of 40% electronic grade HF was slowly added dropwise under stirring at room temperature. The mixture was aged for 60 min, the solid was separated by filtration, and the solid was washed with high-purity water until neutral. The solid was then vacuum dried at 105 ℃ for 8 h to obtain ultra-high purity lead fluoride. The results of ICP testing of this ultra-high purity lead fluoride are shown in Table 6 below.

[0045] Table 6 Summary of ICP test results for ultra-high purity lead fluoride prepared in Example 6

[0046] As can be seen from Table 6, the lead fluoride prepared in Example 6 has a purity of ≥99.9993% and a single metal impurity of ≤0.511ppm. Comparative Example 1 (1) Take 1000 g of industrial grade lead oxide, add 8 L of 15% high-purity acetic acid solution, stir at 70 °C for 2 h, and filter to obtain crude lead acetate aqueous solution.

[0047] (2) A crude lead acetate aqueous solution was injected into a multi-stage countercurrent extraction tower. A mixed organic solvent of ethyl acetate and kerosene was used as the extraction phase. Continuous countercurrent extraction was carried out at room temperature and pressure. The number of extraction stages was 6, and the flow ratio of organic phase to aqueous phase was 1:1. The continuous countercurrent extraction lasted for 2 hours. The aqueous phase and organic phase were separated. The lower layer of lead acetate aqueous solution was collected, and the upper layer of organic phase containing impurities was treated as hazardous waste.

[0048] (3) Prepare a 0.2 mol / L aqueous solution of lead acetate, slowly add 40% ultra-high purity hydrofluoric acid at 25 °C until precipitation is complete, age for 60 min, filter, wash with high-purity water until neutral, and vacuum dry at 105 °C for 8 h to obtain lead fluoride product. The results of ICP detection of this ultra-high purity lead fluoride are shown in Table 7 below.

[0049] Table 7 Summary of ICP test results for lead fluoride prepared in Comparative Example 1

[0050] As can be seen from Table 7, the lead fluoride prepared in Comparative Example 1 has a purity of approximately 99.31%, with relatively high levels of single metallic impurities and a water content of 0.1%.

[0051] Comparative Example 2 (1) Take 1000 g of industrial lead oxide, add 8 L of 15% high-purity acetic acid solution, react at 70℃ for 2 h, filter, concentrate and dry to obtain crude lead acetate.

[0052] (2) Take 1000 g of crude lead acetate and directly load it into the supercritical extraction vessel without adding a complexing agent. Turn on the SCC-CO2 extraction system: pressure 25 MPa, temperature 50℃, CO2 flow rate 10 L / min, static extraction for 0.5 h, dynamic extraction for 1.5 h, and then depressurize to obtain lead acetate.

[0053] (3) The purified lead acetate was prepared into a 0.2 mol / L aqueous solution. 1.1 times the theoretical amount of 40% electronic grade HF was slowly added dropwise under stirring at room temperature. The mixture was aged for 60 min, the solid was separated by filtration, and the solid was washed with high-purity water until neutral. It was then vacuum dried at 105 ℃ for 8 h to obtain lead fluoride. The results of ICP testing of this ultra-high purity lead fluoride are shown in Table 8 below.

[0054] Table 8 Summary of ICP test results for lead fluoride prepared in Comparative Example 2

[0055] As can be seen from Table 8, the purity of the lead fluoride prepared in Comparative Example 2 was approximately 99.2%, with relatively high levels of single metallic impurities and a water content of 0.1%.

[0056] In summary, the method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction provided by this invention uses supercritical CO2 as a non-polar extraction medium, exhibiting extremely low solubility for strongly polar, ionic compounds. Lead acetate, a strongly polar ionic organic salt with high lattice energy, is almost insoluble and does not leak in the SCC-CO2 system, remaining stably in the extraction vessel as a solid phase. Cu, which is associated with the raw materials... 2+ Fe 3+ Zn 2+ Cd 2+ Bi 3+ Impurity metal ions, under the action of a complexing agent, form weakly polar, fat-soluble metal complexes, which can be efficiently extracted by supercritical CO2 and continuously carried out of the system, achieving deep separation of lead acetate from impurities. Ultra-high purity lead acetate purified by SCC-CO2 reacts with ultra-high purity hydrofluoric acid to directly produce 5N grade ultra-high purity lead fluoride with a purity ≥99.995%. This method is suitable for industrial production due to its simple process, environmental friendliness, high impurity removal depth, and stable preparation of 5N grade ultra-high purity lead fluoride.

[0057] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction, characterized in that, Includes the following steps: S1, Acetic acidification to synthesize crude lead acetate: Lead oxide is added to an acetic acid solution, heated to react, and the insoluble matter is filtered to obtain a crude lead acetate solution; the crude lead acetate solution is concentrated under reduced pressure to obtain crude lead acetate solid; S2, Supercritical complex extraction and purification: The crude lead acetate solid described in S1 is mixed with the complexing agent and then loaded into a supercritical extraction vessel. CO2 is introduced to the supercritical state, and dynamic or static supercritical complex extraction is performed to obtain ultra-high purity lead acetate. S3, Preparation of ultra-high purity lead fluoride: Electronic grade hydrofluoric acid is added to the solution of ultra-high purity lead acetate described in S2, and the reaction yields lead fluoride precipitate; the lead fluoride precipitate is aged, filtered, washed and dried to obtain 5N grade ultra-high purity lead fluoride product.

2. The method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction according to claim 1, characterized in that, The mass concentration of the acetic acid solution in S1 is 14-16%, and the acetic acid is high-purity acetic acid; the molar ratio of lead oxide to acetic acid in the acetic acid solution is 1:(4-5).

3. The method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction according to claim 1, characterized in that, The heating reaction in S1 is carried out at a temperature of 60~80℃ for 1~3h; the crude lead acetate solution is concentrated under reduced pressure at a vacuum of -0.085~-0.09Mpa and a temperature of 45~60℃ for 8~20h.

4. The method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction according to claim 1, characterized in that, The amount of complexing agent added in S2 is 0.8 to 1.5% of the mass of the crude lead acetate solid; the complexing agent includes any one or more of diethyldithiocarbamate, di(2-ethylhexyl) phosphate, trioctylphosphine oxide and 2-ethylhexylphosphonate mono-2-ethylhexyl ester.

5. The method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction according to claim 1, characterized in that, The supercritical complex extraction step described in S2 includes: S21, turn on the SCC-CO2 extraction system, set the extraction pressure to 20~30MPa, the extraction temperature to 40~60℃, introduce CO2, keep the extraction temperature and pressure constant, and perform static extraction for 25~35min; S22, open the CO2 inlet and outlet valves to continuously feed supercritical CO2 fluid into the supercritical extraction vessel at a CO2 flow rate of 10±0.5 L / min. Maintain dynamic extraction for 1.4~1.6 h to carry out impurity complexes out of the system. The total extraction time is 2 h. S23, stop CO2 feeding, close the inlet and outlet valves, keep the extraction reactor sealed, stop heating, wait for the extraction reactor to drop to 25±5℃, open the pressure relief valve, first reduce the pressure to 9~10MPa, then continue to depressurize to atmospheric pressure, open the extraction reactor, collect the solid material from the reactor, and you will get ultra-high purity lead acetate.

6. The method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction according to claim 1, characterized in that, The ultra-high purity lead acetate contains Cu, Fe, Zn, Cd, and Bi contents of ≤1 ppm, and the main content of lead acetate is ≥99.995%.

7. The method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction according to claim 1, characterized in that, The concentration of the ultra-high purity lead acetate solution in S3 is 0.1~0.3 mol / L, and the solvent used for the ultra-high purity lead acetate solution is deionized water.

8. The method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction according to claim 1, characterized in that, The mass concentration of the electronic-grade hydrofluoric acid in S3 is 30-50%; the electronic-grade hydrofluoric acid is added dropwise to the ultra-high purity lead acetate solution at 20-40°C, and the amount of electronic-grade hydrofluoric acid added is 1-1.2 times the theoretical amount.

9. The method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction according to claim 1, characterized in that, The aging time in S3 is 40-80 minutes, and the washing is done with high-purity water until neutral.

10. The method for preparing ultra-high purity lead fluoride from lead oxide based on supercritical complexation extraction according to claim 1, characterized in that, The drying described in S3 is vacuum drying, with a temperature of 100~110℃ and a time of 6~10h.

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