A method for recovering Pt and Ir from waste water electrolysis membrane electrodes

Abstract

This invention provides a method for recovering Pt and Ir from waste water electrolysis membrane electrodes, comprising the following steps: Step S1. Dissolving and separating platinum and iridium: The waste water electrolysis membrane electrode is soaked in an organic solvent and separated to obtain a catalyst mixture residue. The catalyst mixture residue is added to a first reagent and calcined at high temperature to obtain precious metal residue. The precious metal residue is dissolved in hydrochloric acid and filtered to obtain a mixed residue. Then, the mixed residue is dissolved in a solvent and filtered to obtain chloroplatinic acid and iridium residue. The chloroplatinic acid is then reduced and purified to obtain platinum compound or platinum black. Step S2. Separating iridium: The iridium residue is added to a second reagent to oxidize and dissolve the iridium residue into chloroiridium acid and insoluble residue. The chloroiridium acid is oxidized with an oxidant, and then ammonium chloride is added and stirred to precipitate it to obtain ammonium chloroiridate. After purification, iridium compound or iridium black is prepared, and the insoluble residue is dissolved in aqua regia for reuse. This invention adds hydroxide to the precious metal residue during calcination, minimizing mechanical entrainment loss and preventing melt splashing during oxidative calcination.

Description

Technical Field

[0001] This invention relates to the field of precious metal catalyst recovery technology, and in particular to a method for recovering Pt and Ir from waste water electrolysis membrane electrodes. Background Technology

[0002] With the development of new energy technologies, hydrogen energy, as a new secondary energy source, has experienced rapid growth in the market. Hydrogen production mainly includes methods such as water-based hydrogen production, coal-based hydrogen production, natural gas-based hydrogen production, biomass-based hydrogen production, photocatalytic hydrogen production, thermochemical hydrogen production, and industrial by-product hydrogen production. Currently, water splitting for hydrogen production is mainly carried out through photocatalytic water splitting and electrolytic water splitting. Electrolytic water splitting has advantages over photochemical methods. Researchers have been working to reduce the potential by improving electrodes, catalysts, and electrolytes. Among these, the most researched approach is to use catalysts to accelerate water splitting. Platinum and iridium, as well as their compounds, are considered the best catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).

[0003] The anode of the membrane electrode catalytic layer for hydrogen production by water electrolysis is mainly composed of Ir catalyst, and the cathode is mainly composed of Pt / C catalyst. However, after working for a certain period of time, Pt / C catalyst and Ir catalyst will gradually become ineffective due to poisoning, agglomeration and other reasons. In addition, my country has scarce precious metal resources, and precious metal catalysts must be recycled and reused after they become ineffective.

[0004] The membrane electrode recovery process for hydrogen production via water electrolysis typically involves separating the catalyst from the proton exchange membrane using organic solvents such as ethanol, resulting in a mixture. This mixture is then calcined at high temperatures to remove carbon, yielding platinum-iridium slag. Aqua regia is used to dissolve and filter the slag, resulting in crude chloroplatinic acid and iridium slag. Finally, the chloroplatinic acid and iridium slag are refined and purified to obtain platinum and iridium as the final products. Because the Pt, Ir, and C mixture contains high levels of metals and exhibits strong catalytic activity, conventional processes using direct calcination to remove carbon and enrich precious metals generate large amounts of smoke and even open flames. Precious metals are lost with the smoke, reducing the recovery rate. For iridium dissolution, conventional processes generally employ medium-temperature alkaline dissolution and aqueous solution chemical dissolution. The medium-temperature melting method typically involves dissolving iridium in a high-temperature molten state by mixing sodium peroxide, sodium hydroxide, and iridium in a specific ratio.

[0005] Sodium peroxide is highly corrosive, and iron, nickel, or corundum crucibles used to hold materials are easily corroded at high temperatures, introducing metallic impurities such as iron, nickel, or aluminum into the iridium solution, increasing the difficulty of iridium purification. The aqueous solution chemical dissolution method uses hydrochloric acid and chlorine to dissolve iridium. Since chlorine is highly corrosive and toxic, it places high demands on the sealing and corrosion resistance of the equipment and poses significant safety risks. Summary of the Invention

[0006] The purpose of this invention is to overcome and supplement the deficiencies in the existing technology, and to provide a method for recovering Pt and Ir from waste water electrolysis membrane electrodes. The purification of Pt and Ir is simple and has low safety risks.

[0007] The technical solution adopted in this invention is:

[0008] A method for recovering Pt and Ir from waste water electrolysis membrane electrodes, comprising the following steps:

[0009] Step S1. Dissolving and separating platinum and iridium: Waste electrolyzed water membrane electrode is provided. The raw material of the anode catalyst layer of the waste electrolyzed water membrane electrode is iridium catalyst, the raw material of the cathode catalyst layer is Pt / C catalyst, and the proton exchange membrane is perfluorosulfonic acid proton exchange membrane. The waste electrolyzed water membrane electrode is soaked in an organic solvent and separated to obtain a catalyst mixture residue. Then, the catalyst mixture residue is added to the first reagent and calcined at high temperature to obtain a precious metal residue. The precious metal residue is added to hydrochloric acid for dissolution and filtration to obtain a mixture residue. Then, the mixture residue is added to a solvent for dissolution and filtration to obtain chloroplatinic acid and iridium residue. After chloroplatinic acid is reduced and purified, platinum compound or platinum black is obtained.

[0010] Step S2. Separation of iridium: The iridium slag from step S1 is slowly added to the second reagent, heated and stirred to oxidize and dissolve the iridium slag into chloroiridic acid and insoluble slag. Then, chloroiridic acid is added to an oxidant for oxidation, and ammonium chloride is added and stirred to precipitate it to obtain ammonium chloroiridate. After purification, ammonium chloroiridate is prepared into iridium compound or iridium black, and the insoluble slag is dissolved by aqua regia and reused.

[0011] Preferably, in the method for recovering Pt and Ir from waste water electrolysis membrane electrodes, the first reagent in step S1 is selected from one of calcium hydroxide, iron hydroxide, barium hydroxide, and strontium hydroxide, the mass ratio of the first reagent to the catalyst residue is 3 to 7:1, the high-temperature calcination temperature is 500 to 800°C, and the calcination time is 3 to 7 hours.

[0012] Preferably, in the method for recovering Pt and Ir from waste water electrolysis membrane electrodes, the mass ratio of hydrochloric acid to the first reagent in step S1 is 1-4:1, the heating and dissolution time is 2-5 hours, and the dissolution temperature is 50-80°C.

[0013] Preferably, in the method for recovering Pt and Ir from waste water electrolysis membrane electrodes, the solvent in step S1 includes hydrochloric acid and sodium chlorate, the mass ratio of the mixed residue, hydrochloric acid and sodium chlorate is 1:4-6:1-2, the dissolution time is 2-5 hours, the alkali is sodium carbonate, the pH is adjusted to 7-8 after purification, and iridium hydroxide precipitate and sodium chloroplatinate solution are obtained by filtration.

[0014] Preferably, in the method for recovering Pt and Ir from waste water electrolysis membrane electrodes, the second reagent in step S2 is chloroauric acid, the concentration of gold in the chloroauric acid is 200-400 g / L, the acidity of the chloroauric acid is 7-15 mol / L, the oxidation and dissolution temperature is 80-130℃, and the reaction time is 4-8 h; the mass ratio of chloroauric acid liquid to iridium powder is 7-13:1.

[0015] Preferably, in the method for recovering Pt and Ir from waste water electrolysis membrane electrodes, the oxidant in step S2 is hydrogen peroxide and 63% nitric acid, the mass ratio of hydrogen peroxide: 63% nitric acid: iridium in chloroiridic acid is 2-4:2-4:1; the mass ratio of iridium in chloroiridic acid: ammonium chloride is 1:7-15, and the stirring time is 1-6 hours.

[0016] Preferably, in the method for recovering Pt and Ir from waste water electrolysis membrane electrodes, the non-melting slag in step S2 is gold slag, the mass ratio of hydrochloric acid:nitric acid:gold slag is 3-6:1-2:1, the dissolution temperature is 60-80℃, and the dissolution reaction time is 4-6h.

[0017] Advantages of this invention:

[0018] (1) The method of recovering Pt and Ir from waste electrolytic water membrane electrodes of the present invention adopts the method of roasting to remove carbon. The addition of hydroxide can make the precious metal slag mixed in the oxide during the roasting process, minimizing mechanical encapsulation loss. It can also prevent melt splashing and loss during oxidative roasting. The hydroxide decomposes to obtain CaO and H2O. H2O reacts with C to generate CO and H2, which can also accelerate the decomposition of C.

[0019] (2) The method of recovering Pt and Ir from waste electrolytic water membrane electrodes of the present invention uses chloroauric acid solution to oxidize and dissolve iridium powder instead of conventional alkaline melting process, which can reduce the energy consumption generated by high-temperature calcination. Since iron crucibles, nickel crucibles, corundum crucibles, etc. are not resistant to sodium oxide corrosion, base metals will exceed the standard during the dissolution process. The oxidation dissolution process does not use sodium salts, and the sodium in the subsequent chloroiridium acid will not exceed the standard, and a large amount of water is not needed to wash sodium, thus reducing the amount of washing water used. Chloroiridium acid does not introduce other impurities, and there is no need to use resin to adsorb base metals. This not only optimizes the process flow, but also reduces the large amount of washing water, hydrochloric acid and other hazardous waste generated after resin washing and acid hydrolysis, and the process is less dangerous.

[0020] (3) The present invention provides a method for recovering Pt and Ir from waste electrolytic water membrane electrodes. The base metal dissolved in the process is used as a by-product, and chloroauric acid is returned to the process for continued use. No secondary waste is generated in the entire process. The process is safer and more environmentally friendly, the process is more convenient, the energy consumption is low, the cost is low, and it is easy to operate. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the method for recovering Pt and Ir from waste water electrolysis membrane electrodes according to the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0023] This invention provides a method for recovering Pt and Ir from waste water electrolysis membrane electrodes. The method involves adding hydroxides via calcination to remove carbon. The hydroxides decompose to yield CaO and H2O. H2O reacts with carbon to produce CO and H2, thus accelerating the decomposition of carbon. The reaction equation is as follows:

[0024]

[0025] 1) The reaction equation for the oxidation and dissolution of iridium powder by chloroauric acid solution is as follows:

[0026] HAuCI4+Ir+2HCI=H3IrCI6+Au↓

[0027] Example 1

[0028] A method for recovering Pt and Ir from waste water electrolysis membrane electrodes, comprising the following steps:

[0029] Step S1. Dissolution and separation of platinum and iridium: Waste water electrolysis membrane electrode is provided. The raw material for the anode catalyst layer of the waste water electrolysis membrane electrode is an iridium catalyst, the raw material for the cathode catalyst layer is a Pt / C catalyst, the proton exchange membrane is a perfluorosulfonic acid proton exchange membrane, and the iridium coating amount is 2 mg / cm³. 2 The cathode is a Pt / C catalyst with a platinum coating of 1 mg / cm³. 2 The carbon coating amount is 0.6 mg / cm². 2 A total of 100 25cm sheets 2The membrane electrode was immersed in an organic solvent, and 13g of catalyst mixture residue was obtained through conventional separation and concentration. Then, 40g of calcium hydroxide was added to the catalyst mixture residue, stirred until homogeneous, and calcined at 700℃ for 5 hours to obtain 30g of precious metal residue. The precious metal residue was added to 110ml of... In a 36% hydrochloric acid solution, heating at 60°C for 4 hours to dissolve and filter yields a calcium chloride solution and 7.28g of a platinum-iridium mixed residue. The platinum-iridium mixed residue is then added to hydrochloric acid and sodium chlorate and heated to dissolve, yielding chloroplatinic acid and iridium residue. The mass ratio of platinum-iridium mixed residue:hydrochloric acid:sodium chlorate is 1:3:1. The heating temperature is 70°C, and the reaction is carried out for 4 hours to obtain chloroplatinic acid and iridium residue. The iridium residue is ground into iridium powder. The chloroplatinic acid is then reduced and purified to obtain platinum compounds or platinum black. The chloroplatinic acid is concentrated to obtain 6.7g of a 38.1% chloroplatinic acid solution. If the iridium content in the chloroplatinic acid is >5ppm, sodium hydroxide is added to adjust the pH to 7-7.5. Filtering yields iridium hydroxide precipitate. The iridium hydroxide is mixed with the iridium powder for the next step, resulting in a 100% direct recovery rate of platinum. The chloroplatinic acid is reduced with hydrazine hydrate to obtain 2.5g of platinum black.

[0030] Step S2. Iridium Separation: Slowly add the iridium slag from Step S1 to 16.7 ml of chloroauric acid with a gold content of 300 g / L. The hydrochloric acid concentration of the chloroauric acid is 10 mol. Heat to 100℃ and stir for 4 hours to oxidize and dissolve the iridium slag into chloroauric acid and gold powder. Concentrate the chloroauric acid to obtain 14.16 g of 35.3% chloroauric acid solution. Then boil the chloroauric acid and add 15 ml of hydrogen peroxide and 15 ml of 63% nitric acid for oxidation. Add 45 g of ammonium chloride and stir for 2 hours to precipitate ammonium chloroauric acid. Purify the ammonium chloroauric acid to prepare iridium compounds or iridium black. Add the gold powder to aqua regia to redissolve and filter to obtain chloroauric acid for reuse. The mass ratio of hydrochloric acid:nitric acid:gold slag is 5:1:1. The dissolution temperature is 60℃ and the dissolution reaction time is 5 hours. The undissolved product is iridium powder, which is returned to the previous step for further oxidation and dissolution.

[0031] Example 2

[0032] A method for recovering Pt and Ir from waste water electrolysis membrane electrodes, comprising the following steps:

[0033] Step S1. Dissolution and separation of platinum and iridium: Waste water electrolysis membrane electrode is provided. The raw material for the anode catalyst layer of the waste water electrolysis membrane electrode is an iridium catalyst, the raw material for the cathode catalyst layer is a Pt / C catalyst, the proton exchange membrane is a perfluorosulfonic acid proton exchange membrane, and the iridium coating amount is 2 mg / cm³. 2 The cathode is a Pt / C catalyst with a platinum coating of 1 mg / cm³. 2 The carbon coating amount is 0.6 mg / cm². 2. A total of 500 25cm sheets 2The membrane electrode was immersed in an organic solvent, and 60g of catalyst mixture residue was obtained through conventional separation and concentration. Subsequently, 180g of calcium hydroxide was added to the catalyst mixture residue, stirred until homogeneous, and calcined at 700℃ for 5 hours to obtain 135g of precious metal residue. The precious metal residue was then added to 500ml of... In a 36% hydrochloric acid solution, calcium chloride solution and 37.3g of platinum-iridium mixed residue were obtained by heating at 60℃ for 4 hours and filtering. Then, the platinum-iridium mixed residue was added to hydrochloric acid and sodium chlorate, heated and dissolved, and filtered to obtain chloroplatinic acid and iridium residue. The mass ratio of platinum-iridium mixed residue: hydrochloric acid: sodium chlorate was 1:3:1. The heating temperature was 70℃ and the reaction was carried out for 4 hours. The iridium residue was ground into iridium powder. After reduction and purification of chloroplatinic acid, platinum compound or platinum black was obtained. The chloroplatinic acid was concentrated to obtain 33g of 38% chloroplatinic acid solution. If the iridium content in the chloroplatinic acid was >5ppm, sodium hydroxide was added to adjust the pH to 7-7.5. The iridium hydroxide precipitate was obtained by filtration. The iridium hydroxide and iridium powder were mixed and proceeded to the next step. The yield of platinum was 100%. Chloroplatinic acid was reduced with hydrazine hydrate to obtain 12.5g of platinum black.

[0034] Step S2. Iridium Separation: Slowly add the iridium slag from Step S1 to 83.4g of chloroauric acid with a gold content of 300g / L. The hydrochloric acid concentration of the chloroauric acid is 10mol. Heat to 100℃ and stir for 4h to oxidize and dissolve the iridium slag. Filter to obtain chloroauric acid and gold powder. Concentrate the chloroauric acid to obtain 71g of 35.2% chloroauric acid solution. Then boil the chloroauric acid and add 75ml of hydrogen peroxide and 75ml of 63% nitric acid for oxidation. Add 250g of ammonium chloride and stir for 2h to precipitate ammonium chloroauric acid. Purify the ammonium chloroauric acid to prepare iridium compounds or iridium black. Add the gold powder to aqua regia to redissolve and filter to obtain chloroauric acid for reuse. The mass ratio of hydrochloric acid:nitric acid:gold slag is 5:1:1. The dissolution temperature is 60℃ and the dissolution reaction time is 5h. The undissolved product is iridium powder, which is returned to the previous step for further oxidation and dissolution.

[0035] Comparative Example 1

[0036] Step S1. This Comparative Example 1 and Example 1 use the same batch of waste membrane electrode catalyst with the same coating amount. Waste membrane electrodes are used as raw materials, and the anode catalyst layer is an iridium catalyst with an iridium coating amount of 2 mg / cm³. 2 The cathode is a Pt / C catalyst with a platinum coating of 1 mg / cm³. 2 The carbon coating amount is 0.6 mg / cm². 2 A total of 100 25cm sheets 2The membrane electrode was immersed in an organic solvent and separated and concentrated using conventional processes to obtain approximately 14g of wet catalyst residue. The wet catalyst residue was then calcined in a muffle furnace at 700℃ for 5 hours to obtain approximately 6.2g of platinum-iridium mixed residue. The platinum-iridium mixed residue was dissolved in hydrochloric acid with sodium chlorate by heating to obtain chloroplatinic acid, with a platinum:hydrochloric acid:sodium chlorate ratio of 1:3:1. The heating temperature was 70℃, and the reaction was carried out for 4 hours. After filtration, iridium residue was obtained, which was then ground into iridium powder. The chloroplatinic acid was concentrated to obtain 5.77g of chloroplatinic acid solution with a platinum content of 38.1%. If the iridium content in the chloroplatinic acid was >5ppm, sodium hydroxide was added to adjust the pH to 7-7.5. After filtration, iridium hydroxide precipitate was obtained. The iridium hydroxide and iridium powder were mixed and proceeded to the next step. The chloroplatinic acid was reduced with hydrazine hydrate to obtain 2.2g of platinum black.

[0037] Step S2. Approximately 4.3g of iridium hydroxide and iridium powder were added to 18g of sodium peroxide and stirred evenly. The mixture was then calcined in a muffle furnace at 650℃ for 6 hours using a nickel crucible to obtain a gray sodium chloroiridate solid. After cooling, water was added to dissolve the sodium salt, resulting in a black solid suspension. Hydrochloric acid was added to adjust the pH to neutral, and the suspension was transferred to a beaker. 200ml of distilled water was added, and this process was repeated three times, for a total of 600ml of water, to wash the sodium salt. The mixture was filtered to obtain iridium hydroxide residue. Excess hydrochloric acid was then added, and the solution was heated to 80℃ for 4 hours to dissolve the residue, resulting in 9.1g of a chloroiridate solution with an iridium content of 35.1% and 0.8g of iridium infusible slag.

[0038] Comparative Example 2

[0039] Step S1. Comparative Example 2 and Example 2 use the same batch of waste membrane electrode catalyst with the same coating amount. Waste membrane electrodes are used as raw materials, and the anode catalyst layer is an iridium catalyst with an iridium coating amount of 2 mg / cm³. 2 The cathode is a Pt / C catalyst with a platinum coating of 1 mg / cm³. 2 The carbon coating amount is 0.6 mg / cm². 2 A total of 500 25cm sheets 2 The membrane electrode was immersed in an organic solvent and separated and concentrated using conventional processes to obtain approximately 64g of wet catalyst residue. The wet catalyst residue was then calcined in a muffle furnace at 700℃ for 5 hours to obtain approximately 32g of platinum-iridium mixed residue. The platinum-iridium mixed residue was dissolved in hydrochloric acid with sodium chlorate by heating to obtain chloroplatinic acid, with a platinum:hydrochloric acid:sodium chlorate ratio of 1:3:1. The heating temperature was 70℃, and the reaction was carried out for 4 hours. After filtration, iridium residue was obtained, which was then ground into iridium powder to obtain 28.15g of 38% chloroplatinic acid solution. If the iridium content of the chloroplatinic acid was >5ppm, sodium hydroxide was added to adjust the pH to 7-7.5. After filtration, iridium hydroxide precipitate was obtained. The iridium hydroxide and iridium residue were mixed and proceeded to the next step. The chloroplatinic acid was reduced with hydrazine hydrate to obtain 10.7g of platinum black.

[0040] Step S2. After mixing iridium hydroxide and iridium powder, add 96g of sodium peroxide and stir evenly. Then, place the mixture in a nickel crucible in a muffle furnace and calcine at 650℃ for 6 hours to obtain gray sodium chloroiridate solid. After cooling, add water to dissolve the sodium salt to obtain a black solid suspension. Add hydrochloric acid to adjust the pH to neutral, transfer to a beaker, add 600ml of distilled water, and wash the sodium salt repeatedly with water 3 times. Filter to obtain iridium hydroxide residue. Then, add excess hydrochloric acid and heat the liquid temperature to 80℃ for 4 hours to dissolve it, obtaining 49.61g of chloroiridate solution with an iridium content of 35.2% and 3.83g of iridium non-fusible slag.

[0041] The direct harvesting rates of Examples 1-2 and Comparative Examples 1-2 are shown in Tables 1-4.

[0042] Table 1 Comparison of Direct Recovery Rate Evaluation Results for Platinum-Iridium Precious Metal Decarbonization Steps

[0043]

[0044] Table 2 Comparison of Direct Recovery Rate Evaluation Results for Platinum-Iridium Precious Metal Decarbonization Steps

[0045]

[0046] As can be seen from Tables 1 and 2, direct roasting results in the loss of approximately 15% to 17% of precious metals through volatilization of the flue gas generated during the roasting process. However, the method used in this invention can achieve a precious metal recovery rate of 99%.

[0047] Table 3 Comparison of evaluation results for direct recovery rate of chloroiridium acid purity.

[0048]

[0049] Table 4 Comparison of Evaluation Results of Purity and Direct Recovery Rate of Chloroirilic Acid

[0050]

[0051] A comparison of Tables 1-4 reveals that the direct recovery rate of iridium chloroiridium acid prepared by direct roasting to remove carbon and then melting iridium with alkali is only 64-69%, and the Na and Ni impurities in the chloroiridium acid exceed the standard, failing to meet the YS / T595-2006 standard for chloroiridium acid. In contrast, the chloroiridium acid prepared using this invention not only meets industry standards but also achieves a direct recovery rate of over 99.9%.

[0052] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for recovering Pt and Ir from waste water electrolysis membrane electrodes, characterized in that: Includes the following steps: Step S1. Dissolving and separating platinum and iridium: Waste electrolyzed water membrane electrode is provided. The raw material of the anode catalyst layer of the waste electrolyzed water membrane electrode is iridium catalyst, the raw material of the cathode catalyst layer is Pt / C catalyst, and the proton exchange membrane is perfluorosulfonic acid proton exchange membrane. The waste electrolyzed water membrane electrode is soaked in an organic solvent and separated to obtain a catalyst mixture residue. Then, the catalyst mixture residue is added to the first reagent and calcined at high temperature to obtain a precious metal residue. The precious metal residue is added to hydrochloric acid for dissolution and filtration to obtain a mixture residue. Then, the mixture residue is added to a solvent for dissolution and filtration to obtain chloroplatinic acid and iridium residue. After chloroplatinic acid is reduced and purified, platinum compound or platinum black is obtained. Step S2. Separation of iridium: The iridium slag from step S1 is slowly added to the second reagent, heated and stirred to oxidize and dissolve the iridium slag into chloroiridic acid and insoluble slag. Then, chloroiridic acid is added to an oxidant for oxidation, and ammonium chloride is added and stirred to precipitate it to obtain ammonium chloroiridate. After purification of ammonium chloroiridate, iridium compounds or iridium black are prepared, and the insoluble slag is dissolved by aqua regia and reused. The second reagent in step S2 is chloroauric acid, with a gold concentration of 200–400 g / L and an acidity of 7–15 mol / L.

2. The method for recovering Pt and Ir from waste water electrolysis membrane electrodes according to claim 1, characterized in that: In step S1, the first reagent is selected from one of calcium hydroxide, iron hydroxide, barium hydroxide, and strontium hydroxide. The mass ratio of the first reagent to the catalyst residue is 3 to 7:

1. The high-temperature roasting temperature is 500 to 800°C, and the roasting time is 3 to 7 hours.

3. The method for recovering Pt and Ir from waste water electrolysis membrane electrodes according to claim 1, characterized in that: In step S1, the ratio of hydrochloric acid to the first reagent is 1–4:1, the heating and dissolution time is 2–5 hours, and the dissolution temperature is 50–80°C.

4. The method for recovering Pt and Ir from waste water electrolysis membrane electrodes according to claim 1, characterized in that: In step S1, the solvents include hydrochloric acid and sodium chlorate, with a mass ratio of mixed residue, hydrochloric acid and sodium chlorate of 1:4 to 6:1 to 2, and a dissolution time of 2 to 5 hours.

5. The method for recovering Pt and Ir from waste water electrolysis membrane electrodes according to claim 1, characterized in that: The oxidation and dissolution temperature in step S2 is 80–130°C, and the reaction time is 4–8 h; the mass ratio of chloroauric acid liquid to iridium powder is 7–13:

1.

6. The method for recovering Pt and Ir from waste water electrolysis membrane electrodes according to claim 1, characterized in that: In step S2, the oxidant is hydrogen peroxide and 63% nitric acid. The mass ratio of hydrogen peroxide: 63% nitric acid: iridium in chloroiridic acid is 2-4:2-4:1; the mass ratio of iridium in chloroiridic acid to ammonium chloride is 1:7-15, and the stirring time is 1-6 hours.

7. The method for recovering Pt and Ir from waste water electrolysis membrane electrodes according to claim 1, characterized in that: In step S2, the non-melting slag is gold slag, the mass ratio of hydrochloric acid:nitric acid:gold slag is 3-6:1-2:1, the dissolution temperature is 60-80℃, and the dissolution reaction time is 4-6h.

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