A method for extracting iridium and ruthenium from iridium-ruthenium alloy ingot to directly prepare corresponding compounds

Abstract

The present application belongs to the technical field of noble metal extraction, and provides a method for extracting iridium and ruthenium from iridium-ruthenium alloy ingot to directly prepare corresponding compounds. The present application uses a tin and bismuth alloy solution to high-temperature dissolve the extremely difficultly soluble iridium-ruthenium alloy ingot; nitric acid is used to dissolve tin, bismuth, iron, nickel and other base metals; after the acid dissolution, the active powder of noble metal is oxidized and distilled to extract ruthenium, and directly prepare ruthenium trichloride; after the extraction of ruthenium, the active metal powder is dissolved with HCl+Cl2 to dissolve iridium, and the acid is removed through filtration and concentration, and the iridium chloride is directly prepared through ion exchange resin. The present application is aimed at the extremely difficultly soluble ruthenium-iridium alloy ingot to rapidly form liquid, and the extraction and separation of ruthenium and iridium is complete. When ruthenium and iridium are extracted, the high-temperature oxidation melting high energy consumption and the strong corrosion to the equipment are avoided, the separation process is simple, the cost is low, and the present application is suitable for industrialized production.

Description

Technical Field

[0001] This invention relates to the field of precious metal extraction technology, and in particular to a method for directly preparing iridium and ruthenium into corresponding compounds from iridium-ruthenium alloy ingots. Background Technology

[0002] Iridium and ruthenium are insoluble in acids, alkalis, and hot aqua regia, making them among the most difficult precious metals to dissolve into liquids. When platinum group metals (PGMs) such as ruthenium and iridium are enriched from precious metal-containing materials using plasma high-temperature melting, dissolving them in oxidative melting or hot aqua regia to create a liquid solution is extremely difficult. Zhao Huaizhi of the Kunming Institute of Precious Metals, in his article "Phase Analysis of Platinum Group Metal Secondary Resources from Platinum Metals Platinum Metal Secondary Resources," points out that plasma-melted precious metal alloy ingots are an aggregate of multiple non-equilibrium phases. The main phase is a solid solution phase of platinum group metals with Fe or (Fe, Ni) as the matrix. Among these, enriched materials with high silicon content contain silicon compounds of Fe or Ni containing PGMs, and rapid cooling alloying produces ε-Fe metastable and Fe-C metastable phases. Precious metal alloy ingots produced by plasma high-temperature melting are highly corrosion-resistant due to rapid cooling homogenization, posing challenges to subsequent wet extraction of PGMs.

[0003] Chinese patent application CN 101575674A discloses a method for recovering platinum group metals (PGMs) from plasma melting aggregates. The method involves the following dissolution and solution preparation steps: ① leaching the material with concentrated sulfuric acid; ② roasting the sulfuric acid leaching residue; ③ mixing the roasted product with a solid hydroxide followed by alkaline fusion; ④ dissolving the alkaline leaching residue with HCl, etc.; ⑤ replacing the solution with an active metal such as iron; ⑥ dissolving the replaced residue with HCl + H2O2, etc., to obtain a PMM-rich solution. The rich solution contains small amounts of copper and zinc, and trace amounts of lead, tin, and iron. While this method solves the problem of transferring precious metals from highly corrosion-resistant plasma-melted alloy ingots into the solution, the solution preparation process is complex and cumbersome, requiring harsh conditions such as strong acids, strong alkalis, and high temperatures, causing severe equipment corrosion and significant environmental pollution.

[0004] Chinese patent application CN 1428445A discloses a method for extracting osmium, iridium, and ruthenium. This method involves crushing zinc and aluminum alloy materials; pyrometallurgically distilling osmium; leaching the residue with sodium peroxide; and precipitating ruthenium from the leachate with ethanol. The iridium-containing aqueous leaching residue is then leached with an 8 mol / L HCl solution to remove iridium, and 10% sodium sulfide is used to remove platinum, palladium, and rhodium impurities. Finally, ammonium chloroiridate is oxidized and precipitated. This method uses hydrochloric acid or sulfuric acid solution to dissolve the alloy block, generating a large amount of hydrogen gas, posing a flammable and explosive risk to the operating equipment and environment. Before preparing the ruthenium-iridium alloy block into a solution, a stringent sodium peroxide (Na2O2) melting process is required to convert it into the corresponding ruthenium-iridium oxides.

[0005] Therefore, how to provide a precious metal extraction process that is simple, low-cost, and has good extraction effect has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a method for extracting iridium and ruthenium from iridium-ruthenium alloy ingots and directly preparing the corresponding compounds. Its purpose is to solve the technical problems of complex and high-risk processes in existing precious metal extraction methods.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a method for extracting iridium and ruthenium from iridium-ruthenium alloy ingots and directly preparing the corresponding compounds, comprising the following steps:

[0009] S1. Bismuth ingots and tin ingots are mixed and melted to obtain a mixed molten liquid;

[0010] S2. The mixed molten liquid and iridium-ruthenium alloy ingot are mixed and then melted to obtain the molten liquid;

[0011] S3. The molten liquid is rapidly cooled to obtain an alloy block. The alloy block is mixed with nitric acid and dissolved. After filtration, the precious metal active powder is obtained.

[0012] S4. Ruthenium trichloride is obtained by sequentially washing, distilling with chlorine and alkali, absorbing with hydrochloric acid, concentrating, crystallizing and drying the precious metal active powder.

[0013] S5. After extracting ruthenium in step S4, the iridium-containing active metal powder and dilute hydrochloric acid are mixed and then filtered and washed sequentially. The washed iridium-containing active metal powder is mixed with concentrated hydrochloric acid to obtain a slurry. Chlorine gas is introduced into the slurry to perform chlorination to obtain a solution containing H2IrCl6.

[0014] S6. The solution containing H2IrCl6 is concentrated sequentially, hydrochloric acid is removed, and then passed through an ion exchange resin to obtain a chloroiridium acid solution; or the solution containing H2IrCl6 is mixed with ammonium chloride to obtain ammonium chloroiridium crystals.

[0015] Furthermore, in step S1, the mass ratio of bismuth ingot to tin ingot is 1:0.1 to 10; the melting temperature is 300 to 500°C; and the melting time is 10 to 60 minutes.

[0016] Furthermore, in step S2, the melting temperature is 1100–1400°C, and the melting time is 30–60 min.

[0017] Furthermore, the total mass ratio of bismuth and tin ingots to the mass ratio of iridium-ruthenium alloy ingots is 2 to 6:1.

[0018] Furthermore, in step S3, the quenching time is 5–30 min; the concentration of the nitric acid is 2–7 mol / L; and the solid-liquid ratio of the alloy block to the nitric acid is 1 kg: 20–60 L.

[0019] Furthermore, in step S5, the concentration of dilute hydrochloric acid is 0.1–1 mol / L, and the solid-liquid ratio of iridium metal active powder to dilute hydrochloric acid is 1 kg: 10–20 L.

[0020] Furthermore, in step S5, the mass fraction of concentrated hydrochloric acid is 36-38%, and the solid-liquid ratio of iridium metal active powder to concentrated hydrochloric acid is 1 kg: 20-50 L.

[0021] Furthermore, in step S5, the chlorine flow rate is 50–120 mL / min, the chlorination temperature is 80–100 °C, and the chlorination time is 4–18 h.

[0022] Furthermore, the washing in steps S4 and S5 is done independently with water until the pH of the filtrate is ≥3.

[0023] Furthermore, in step S6, the cation exchange resin is one or two of D001 exchange resin, D152 exchange resin, 110 exchange resin, 001×7 exchange resin, 001×10 exchange resin, and CH-90Na exchange resin; the flow rate of the chloroiridic acid solution through the cation exchange resin is 100-500 mL / min; and the volume ratio of the cation exchange resin to the chloroiridic acid solution is 0.1-3:1.

[0024] Furthermore, in step S6, the solid-liquid ratio of ammonium chloride and the H2IrCl6-containing solution is 50-400 g: 1 L.

[0025] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. This invention utilizes a high-temperature plasma melting process to produce noble metal alloy ingots from low-melting-point, platinum-group-friendly tin and bismuth metal ingots. This effectively destroys the following highly corrosion-resistant phases that are insoluble in aqua regia: ① a solid solution phase of platinum group metal alloys with Fe or (Fe, Ni) as the matrix; ② a silicon compound phase containing platinum group metals (Fe or Ni); ③ the ε-Fe metastable phase and Fe-C metastable phase generated during the rapid cooling alloying process in plasma melting. This facilitates the rapid and thorough distillation extraction and separation of ruthenium, as well as the dissolution and solution preparation of iridium.

[0027] 2. Compared with the prior art, the present invention can completely distill out ruthenium in a single oxidation distillation, with extremely high ruthenium distillation efficiency, and avoids the use of flammable and explosive peroxide reagents that severely corrode furnace equipment.

[0028] 3. Nitric acid is used to dissolve base metals. This process does not produce flammable and explosive hydrogen gas, making the operating environment safer and requiring less stringent safety standards for the equipment.

[0029] 4. Oxidative distillation to extract ruthenium and prepare ruthenium trichloride is carried out in a self-made reaction device. It has the characteristics of simple process, low energy consumption, fewer distillation times, short reaction time, ruthenium trichloride product with impurity elements meeting the standards, easy quality control, and high product yield.

[0030] 5. The separation and extraction process of the present invention is simple and can directly process the ruthenium and iridium contained in the material into qualified ruthenium trichloride and chloroiridium acid and chloroiridium ammonium compounds. It is low in cost and suitable for industrial production.

[0031] 6. The precious metal extraction process of the present invention is applicable to the processing of precious metal alloy ingots, pure iridium ingots, iridium-ruthenium ingots, and aqua regia-insoluble residues containing ruthenium and iridium, which are obtained by plasma high-temperature melting and have extremely strong corrosion resistance and are extremely difficult to prepare into liquids. Attached Figure Description

[0032] Figure 1 This is a process flow diagram of the present invention for extracting iridium and ruthenium from iridium-ruthenium alloy ingots and directly preparing the corresponding compounds;

[0033] Figure 2 This is a diagram of the apparatus used in step S4 of the present invention to prepare ruthenium trichloride. Detailed Implementation

[0034] This invention provides a method for extracting iridium and ruthenium from iridium-ruthenium alloy ingots and directly preparing the corresponding compounds, comprising the following steps:

[0035] S1. Bismuth ingots and tin ingots are mixed and melted to obtain a mixed molten liquid;

[0036] S2. The mixed molten liquid and iridium-ruthenium alloy ingot are mixed and then melted to obtain the molten liquid;

[0037] S3. The molten liquid is rapidly cooled to obtain an alloy block. The alloy block is mixed with nitric acid and dissolved. After filtration, the precious metal active powder is obtained.

[0038] S4. Ruthenium trichloride is obtained by sequentially washing, distilling with chlorine and alkali, absorbing with hydrochloric acid, concentrating, crystallizing and drying the precious metal active powder.

[0039] S5. After extracting ruthenium in step S4, the iridium-containing active metal powder and dilute hydrochloric acid are mixed and then filtered and washed sequentially. The washed iridium-containing active metal powder is mixed with concentrated hydrochloric acid to obtain a slurry. Chlorine gas is introduced into the slurry to perform chlorination to obtain a solution containing H2IrCl6.

[0040] S6. The solution containing H2IrCl6 is concentrated sequentially, hydrochloric acid is removed, and then passed through an ion exchange resin to finally obtain a chloroiridium acid solution; or the solution containing H2IrCl6 is mixed with ammonium chloride to obtain ammonium chloroiridium crystals.

[0041] In this invention, in step S1, the mass ratio of bismuth ingot to tin ingot is 1:0.1 to 10, preferably 1:1 to 8, and more preferably 1:3 to 6; the melting temperature is 300 to 500°C, preferably 350 to 450°C, and more preferably 400°C; the melting time is 10 to 60 min, preferably 20 to 50 min, and more preferably 30 min.

[0042] In this invention, in step S2, the melting temperature is 1100-1400℃, preferably 1150-1350℃, and more preferably 1200-1300℃; the melting time is 30-60 min, preferably 40-50 min, and more preferably 45 min.

[0043] In this invention, the total mass ratio of bismuth ingots and tin ingots to the mass ratio of iridium-ruthenium alloy ingots is 2 to 6:1, preferably 3 to 5:1, and more preferably 4:1.

[0044] In this invention, in step S3, the quenching time is 5-30 min, preferably 5-15 min, and more preferably 10 min; the concentration of the nitric acid is 2-7 mol / L, preferably 3-6 mol / L, and more preferably 4-5 mol / L; the solid-liquid ratio of the alloy block to the nitric acid is 1 kg: 20-60 L, preferably 1 kg: 30-50 L, and more preferably 1 kg: 40 L.

[0045] In this invention, the instruments and apparatus used in step S4 are described below. Figure 2 The specific steps for preparing ruthenium trichloride from precious metal active powder are as follows:

[0046] ① Add a 20-40% NaOH solution under negative pressure in a closed state. The material ratio of the precious metal active powder and the sodium hydroxide solution is 1:10-100.

[0047] ② Heat to 80℃, introduce chlorine gas into step ① at a flow rate of 50-120 mL / min, and control the reaction temperature at 105℃ to generate yellow RuO4 gas;

[0048] ③ The RuO4 gas generated in step ② is purified by deionized water and then passed into a multi-stage hydrochloric acid absorption solution for absorption. The hydrochloric acid concentration is 2-10 mol / L, and the temperature is controlled at 25-40℃. A reducing agent is added to the hydrochloric acid absorption solution. The reducing agent is one or a mixture of two of methanol, ethanol, n-propanol and isopropanol, and the mass fraction of the reducing agent is 0.01-6%. The reaction produces a brownish-red H2RuCl5 solution. The tail gas is then passed into a 15% NaOH solution under negative pressure for absorption.

[0049] ④ The H2RuCl5 generated in step ③ was concentrated by conventional heating, crystallized and dried by infrared to obtain dark brown RuCl3 crystals.

[0050] In this invention, in step S5, the concentration of dilute hydrochloric acid is 0.1-1 mol / L, preferably 0.2-0.8 mol / L, and more preferably 0.4-0.6 mol / L; the solid-liquid ratio of iridium metal active powder and dilute hydrochloric acid is 1 kg: 10-20 L, preferably 1 kg: 12-18 L, and more preferably 1 kg: 14-16 L.

[0051] In this invention, in step S5, the mass fraction of concentrated hydrochloric acid is 36-38%, preferably 37%; the solid-liquid ratio of iridium metal active powder to concentrated hydrochloric acid is 1kg:20-50L, preferably 1kg:30-40L, and more preferably 1kg:35L.

[0052] In this invention, in step S5, the flow rate of chlorine gas is 50-120 mL / min, preferably 60-100 mL / min, and more preferably 70-80 mL / min; the chlorination temperature is 80-100℃, preferably 85-95℃, and more preferably 90℃; and the chlorination time is 4-18 h, preferably 5-15 h, and more preferably 8-12 h.

[0053] In this invention, the washing in steps S4 and S5 is done independently with water until the pH of the filtrate is ≥3, preferably ≥3.5, and more preferably ≥4.

[0054] In this invention, in step S6, the ion exchange resin is one or two of D001 exchange resin, D152 exchange resin, 110 exchange resin, 001×7 exchange resin, 001×10 exchange resin, and CH-90Na exchange resin; the flow rate of the chloroiridic acid solution through the ion exchange resin is 100-500 mL / min, preferably 200-400 mL / min, more preferably 250-350 mL / min, and more preferably 300 mL / min; the volume ratio of the ion exchange resin to the chloroiridic acid solution is 0.1-3:1, preferably 0.5-2.6:1, more preferably 1-2.1:1, and more preferably 1.5:1.

[0055] In this invention, in step S6, the solid-liquid ratio of ammonium chloride and H2IrCl6 solution is 50-400 g:1 L, preferably 150-350 g:1 L, and more preferably 300 g:1 L.

[0056] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0057] Example 1

[0058] A batch of iridium-ruthenium alloy ingots produced by plasma melting enrichment method has the following main components: Ru: 15.72%, Ir: 20.23%, Fe: 46.06%, Ni: 13.28%, Cu: 4.21%, Pd: 0.49%, with the balance being unavoidable impurities.

[0059] Take 800g of bismuth ingot and 200g of tin ingot and put them into a 4kg melting cup. Heat to 300℃ and melt the metal ingots for 50 minutes. Add 400g of the above-mentioned self-produced iridium-ruthenium alloy ingot, heat to 1200℃ and hold for 30 minutes to make it into a liquid phase. Stir evenly with a quartz rod, pour out and pour onto an iron plate and cool rapidly for 20 minutes to form an alloy block. Transfer the alloy block to an acid-resistant plastic bucket and gradually pour 4mol / L nitric acid into the bucket. Filter out the solution containing base metals such as bismuth, tin, and iron. Add 4mol / L nitric acid again to dissolve and filter out the solution containing base metals. Repeat this process 3 times, 10L each time, for a total of 30L of nitric acid. The precious metal active powder was filtered out and washed with deionized water until the pH of the filtrate was ≥3. The filtrate was then transferred to a reactor. Under closed conditions, 5 L of 30% NaOH solution was added under negative pressure. 2.5 L of 4 mol / L hydrochloric acid containing 0.5% ethanol was added to the absorption bottle, and 3 L of 15% NaOH solution was added to the tail gas absorption bottle. After the reactor was heated to 80℃, chlorine gas was introduced, and ruthenium was distilled at a controlled temperature of 105℃. After distillation, the H₂RuCl₅ solution in the absorption bottle was removed. The solution was concentrated, crystallized, and dried using infrared spectroscopy to obtain 143.93 g of ruthenium trichloride. The quality met the HG / T 3679-2011 standard, with a ruthenium content of 36.97%.

[0060] After ruthenium extraction, the iridium-containing active metal powder was slurried with 1500 mL of 0.2 mol / L dilute hydrochloric acid, filtered, and washed with deionized water until the filtrate pH was ≥3. The washed active metal powder was then slurried with 8 L of 38% concentrated hydrochloric acid, heated to 85℃, and chlorinated with 100 mL / min under negative pressure for 12 h. The tail gas was absorbed by a 15% NaOH solution under negative pressure. The solid-liquid mixture after iridium dissolution by chlorine + HCl was filtered to separate the H₂IrCl₆ solution, which was then concentrated and the acid removed to obtain a chloroiridium acid solution. The chloroiridium acid solution was passed through the 001×7 exchange resin at a flow rate of 400 mL / min at a volume ratio of 1:0.3, yielding 194.83 g of chloroiridium acid solution. Analysis showed an iridium content of 34.92%, and all impurities met the standards. The iridium chlorination solubility was 94.7%.

[0061] Example 2

[0062] The iridium-ruthenium alloy ingot used in this embodiment is the same as that in Embodiment 1.

[0063] Take 900g of bismuth ingot and 200g of tin ingot and put them into a 4kg melting cup. Heat to 300℃ and melt the metal ingots for 30 minutes. Add 500g of the above-mentioned self-produced iridium-ruthenium alloy ingot, heat to 1300℃ and hold for 30 minutes to make it into a liquid phase. Stir evenly with a quartz rod, pour out and pour onto an iron plate and cool rapidly for 20 minutes to form an alloy block. Transfer the alloy block to an acid-resistant plastic bucket and gradually pour 4mol / L nitric acid into the bucket. Filter out the solution containing base metals such as bismuth, tin, and iron. Add 4mol / L nitric acid again to dissolve and filter out the solution containing base metals. Repeat this process 3 times, with 10L each time for the first two times, and a total of 35L of nitric acid for the last time. The precious metal active powder was filtered out and washed with deionized water until the pH of the filtrate was ≥3. The filtrate was then transferred to a reactor. Under closed conditions, 5 L of 30% NaOH solution was added under negative pressure. 2.5 L of 4 mol / L hydrochloric acid containing 0.5% ethanol was added to the absorption bottle, and 3 L of 15% NaOH solution was added to the tail gas absorption bottle. After the reactor was heated to 80℃, chlorine gas was introduced, and ruthenium was distilled at a controlled temperature of 105℃. After distillation, the H₂RuCl₅ solution in the absorption bottle was removed. The solution was concentrated, crystallized, and dried using infrared spectroscopy to obtain 178.87 g of ruthenium trichloride. The quality met the HG / T 3679-2011 standard, with a ruthenium content of 36.92%.

[0064] After ruthenium extraction, the iridium-containing active metal powder was slurried in 1500 mL of 0.2 mol / L dilute hydrochloric acid, filtered, and washed with deionized water until the pH of the filtrate was ≥3. The washed active metal powder was then slurried in 12 L of 38% concentrated hydrochloric acid, heated to 85℃, and chlorinated under negative pressure at a flow rate of 80 mL / min for 16 h. The tail gas was absorbed by passing it through a 15% NaOH solution under negative pressure. The solid-liquid mixture after iridium dissolution by chlorine + HCl was filtered to separate the H₂IrCl₆ solution, which was then concentrated and the acid removed to obtain a chloroiridium acid solution. The chloroiridium acid solution was passed through the 001×7 exchange resin at a volume ratio of 1:0.3 at a flow rate of 400 mL / min, yielding 248.19 g of chloroiridium acid solution. Analysis showed an iridium content of 34.87%, and all impurities met the standards. The iridium chlorination solubility was 96.37%.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for extracting iridium and ruthenium from iridium-ruthenium alloy ingots and directly preparing the corresponding compounds, characterized in that, Includes the following steps: S1. Bismuth ingots and tin ingots are mixed and melted to obtain a mixed molten liquid; S2. The mixed molten liquid and iridium-ruthenium alloy ingot are mixed and then melted to obtain the molten liquid; S3. The molten liquid is rapidly cooled to obtain an alloy block. The alloy block is mixed with nitric acid and dissolved. After filtration, the precious metal active powder is obtained. S4. Ruthenium trichloride is obtained by sequentially washing, distilling with chlorine and alkali, absorbing with hydrochloric acid, concentrating, crystallizing and drying the precious metal active powder. S5. After extracting ruthenium in step S4, the iridium-containing active metal powder and dilute hydrochloric acid are mixed and then filtered and washed sequentially. The washed iridium-containing active metal powder is mixed with concentrated hydrochloric acid to obtain a slurry. Chlorine gas is introduced into the slurry to perform chlorination to obtain a solution containing H2IrCl6. S6. After sequentially concentrating and removing hydrochloric acid from the H2IrCl6 solution, pass it through an ion exchange resin to obtain a chloroiridium acid solution; or mix the H2IrCl6 solution with ammonium chloride to obtain ammonium chloroiridium crystals. The iridium-ruthenium alloy ingot is a precious metal alloy ingot produced by high-temperature plasma melting.

2. The method according to claim 1, characterized in that, In step S1, the mass ratio of bismuth ingot to tin ingot is 1:0.1~10; the melting temperature is 300~500℃; and the melting time is 10~60min.

3. The method according to claim 2, characterized in that, In step S2, the melting temperature is 1100~1400℃ and the melting time is 30~60min.

4. The method according to claim 2 or 3, characterized in that, The total mass ratio of bismuth and tin ingots to iridium-ruthenium alloy ingots is 2 to 6:

1.

5. The method according to claim 4, characterized in that, In step S3, the rapid cooling time is 5~30 min; the concentration of the nitric acid is 2~7 mol / L; and the solid-liquid ratio of the alloy block to the nitric acid is 1 kg: 20~60 L.

6. The method according to claim 2 or 5, characterized in that, In step S5, the concentration of dilute hydrochloric acid is 0.1~1mol / L, and the solid-liquid ratio of iridium metal active powder to dilute hydrochloric acid is 1kg:10~20L.

7. The method according to claim 6, characterized in that, In step S5, the mass fraction of concentrated hydrochloric acid is 36-38%, and the solid-liquid ratio of iridium metal active powder to concentrated hydrochloric acid is 1 kg: 20-50 L.

8. The method according to claim 7, characterized in that, In step S5, the chlorine flow rate is 50~120mL / min, the chlorination temperature is 80~100℃, and the chlorination time is 4~18h.

9. The method according to claim 2, 5 or 8, characterized in that, The washing in steps S4 and S5 is done independently with water until the pH of the filtrate is ≥3.

10. The method according to claim 9, characterized in that, In step S6, the solid-liquid ratio of ammonium chloride and H2IrCl6 solution is 50~400g:1L; In step S6, the ion exchange resin is one or two of D001 exchange resin, D152 exchange resin, 110 exchange resin, 001×7 exchange resin, 001×10 exchange resin, and CH-90Na exchange resin; the flow rate of the chloroiridic acid solution through the ion exchange resin is 100-500 mL / min; and the volume ratio of the ion exchange resin to the chloroiridic acid solution is 0.1-3:1.

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