A method for extracting metallic iridium from iridium-titanium anode plates

Abstract

The application discloses a method for extracting metallic iridium from iridium-titanium anode plates and relates to the field of precious metal recovery, and comprises the following steps: S1: stripping the coating of the iridium-titanium anode plate to obtain iridium oxide powder; the stripping method is as follows: the iridium-titanium anode plate is soaked in a treatment liquid, then frozen at-40 to-50 DEG C for 10-30 min, then warmed to 70-90 DEG C, and kept warm for 10-20 min, and the freezing-warming cycle is repeated for 3-10 times, finally, a film forming agent containing microorganisms is sprayed on the surface of the iridium-titanium anode plate; the treatment liquid comprises methyl isobutyl ketone, furanone, a surfactant and water; S2: the iridium oxide powder is added into an acid liquid for immersion, insoluble impurities are removed by filtration, a precipitant is added to precipitate iridium, and a precipitate is obtained; S3: the precipitate is washed and dried, then roasted, and the iridium oxide is reduced to metallic iridium powder by hydrogen reduction. The method improves the recovery rate of iridium.

Description

Technical Field

[0001] This invention relates to the field of precious metal recycling technology, specifically to a method for extracting metallic iridium from an iridium-titanium anode plate. Background Technology

[0002] Iridium-titanium anode plates are widely used in chlor-alkali industries, wastewater treatment, and electroplating. The iridium coating on their surface wears off over time. Because iridium is a rare and precious metal (expensive and scarce), discarded anode plates have high recycling value. Therefore, developing efficient and environmentally friendly iridium recycling technologies is crucial.

[0003] Currently, traditional methods mostly employ pyrometallurgy or hydrometallurgy, but these suffer from problems such as low recovery rates. Therefore, improvements are needed. Summary of the Invention

[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a method for extracting metallic iridium from an iridium-titanium anode plate.

[0005] The technical solution of the present invention is as follows: A method for extracting metallic iridium from an iridium-titanium anode plate includes the following steps: S1: Peel off the coating of the iridium-titanium anode plate to obtain iridium oxide powder; The peeling method is as follows: Immerse the iridium-titanium anode plate in the treatment solution, then freeze it at -40°C to -50°C for 10-30 minutes, then raise the temperature to 70-90°C and hold it for 10-20 minutes. Repeat the freezing-heating cycle 3-10 times. Finally, spray a film-forming agent containing microorganisms onto the surface of the iridium-titanium anode plate. The treatment solution includes methyl isobutyl ketone, furanone, surfactant, and water; S2: Immerse the iridium oxide powder in acid solution, filter to remove insoluble impurities, add a precipitant to precipitate the iridium, and obtain the precipitate; S3: After washing and drying, the precipitate is calcined and reduced with hydrogen to reduce iridium oxide to metallic iridium powder.

[0006] Preferably, in step S1, during the heat preservation process, ultrasound is activated.

[0007] Preferably, in step S1, the ultrasonic power is 300-400W and the frequency is 20-30kHz.

[0008] Preferably, in step S1, the mass ratio of methyl isobutyl ketone, furanone, surfactant and water is 40-60:10-20:1-3:30-50.

[0009] Preferably, in step S1, the surfactant is a fatty alcohol polyoxyethylene ether.

[0010] Preferably, in step S1, the microorganism is *Chlorobacterium violaceum* (…). C.violaceum ).

[0011] Preferably, the film-forming agent is a polyvinyl alcohol solution or a chitosan solution.

[0012] Preferably, the acid solution includes hydrochloric acid and nitric acid, and the precipitant is ammonium chloride.

[0013] The beneficial effects of this invention are: This invention discloses a method for extracting metallic iridium from an iridium-titanium anode plate. A specific method is used to peel off the coating on the iridium-titanium anode plate and then recover the metallic iridium. First, the iridium-titanium anode plate is immersed in a treatment solution to cause the organic matter inside to swell. Then, repeated freeze-thaw cycles are performed to loosen the structure of the coating under stress and water molecule volume changes. This, combined with the positive tropism of microorganisms and furanones, allows microorganisms to quickly enter the loose pores to the polymer surface, prompting them to secrete extracellular enzymes, accelerating the swelling and fracture of the material, and accelerating the peeling of the coating from the iridium-titanium anode plate. This reduces iridium loss and increases the iridium recovery rate. Detailed Implementation

[0015] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0016] Example 1 A method for extracting metallic iridium from an iridium-titanium anode plate includes the following steps: S1: Peel off the coating of the iridium-titanium anode plate to obtain iridium oxide powder; The peeling method is as follows: The iridium-titanium anode plate was immersed in the treatment solution, then frozen at -40°C for 20 minutes, followed by heating to 80°C and holding at that temperature for 15 minutes. This freezing-heating cycle was repeated 5 times. Finally, a film-forming agent containing microorganisms was sprayed onto the surface of the iridium-titanium anode plate; the microorganisms were *Synthobacterium violaceum* (Chroma violaceum). C.violaceum The film-forming agent is a 5 wt% chitosan solution, and microorganisms account for 60% of the mass of the film-forming agent.

[0017] The treatment solution comprises methyl isobutyl ketone, furanone, surfactant, and water in a mass ratio of 50:10:2:30; the surfactant is fatty alcohol polyoxyethylene ether.

[0018] When maintaining the temperature, activate the ultrasonic function; the ultrasonic power is 300W and the frequency is 30kHz.

[0019] S2: Immerse the iridium oxide powder in acid solution, filter to remove insoluble impurities, add a precipitant to precipitate the iridium, and obtain the precipitate; The acid solution comprises hydrochloric acid and nitric acid in a volume ratio of 3:1, with the hydrochloric acid concentration being 10 wt% and the nitric acid concentration being 10 wt%, and the precipitant being ammonium chloride.

[0020] S3: After washing and drying, the precipitate is calcined and reduced with hydrogen to reduce iridium oxide to metallic iridium powder.

[0021] Example 2 A method for extracting metallic iridium from an iridium-titanium anode plate includes the following steps: S1: Peel off the coating of the iridium-titanium anode plate to obtain iridium oxide powder; The peeling method is as follows: The iridium-titanium anode plate was immersed in a treatment solution, then frozen at -50°C for 10 minutes, followed by heating to 70°C and holding at that temperature for 10 minutes. This freezing-heating cycle was repeated 8 times. Finally, a film-forming agent containing microorganisms was sprayed onto the surface of the iridium-titanium anode plate; the microorganisms were *Synthobacterium violaceum* (Chroma violaceum). C.violaceum The film-forming agent is a polyvinyl alcohol solution, the film-forming agent is a 5 wt% chitosan solution, and microorganisms account for 60% of the mass of the film-forming agent.

[0022] The treatment solution comprises methyl isobutyl ketone, furanone, surfactant, and water in a mass ratio of 50:10:2:30; the surfactant is fatty alcohol polyoxyethylene ether.

[0023] When maintaining the temperature, activate the ultrasonic function; the ultrasonic power is 300W and the frequency is 30kHz.

[0024] S2: Immerse the iridium oxide powder in acid solution, filter to remove insoluble impurities, add a precipitant to precipitate the iridium, and obtain the precipitate; The acid solution comprises hydrochloric acid and nitric acid in a volume ratio of 3:1, with the hydrochloric acid concentration being 10 wt% and the nitric acid concentration being 10 wt%, and the precipitant being ammonium chloride.

[0025] S3: After washing and drying, the precipitate is calcined and reduced with hydrogen to reduce iridium oxide to metallic iridium powder.

[0026] Example 3 A method for extracting metallic iridium from an iridium-titanium anode plate includes the following steps: S1: Peel off the coating of the iridium-titanium anode plate to obtain iridium oxide powder; The peeling method is as follows: The iridium-titanium anode plate was immersed in a treatment solution, then frozen at -45°C for 25 minutes, followed by heating to 90°C and holding at that temperature for 15 minutes. This freezing-heating cycle was repeated 10 times. Finally, a film-forming agent containing microorganisms was sprayed onto the surface of the iridium-titanium anode plate; the microorganisms were *Synthobacterium violaceum* (Chroma violaceum). C.violaceum The film-forming agent is a polyvinyl alcohol solution, the film-forming agent is a 5 wt% chitosan solution, and microorganisms account for 60% of the mass of the film-forming agent.

[0027] The treatment solution comprises methyl isobutyl ketone, furanone, surfactant, and water in a mass ratio of 50:10:2:30; the surfactant is fatty alcohol polyoxyethylene ether.

[0028] When maintaining the temperature, activate the ultrasonic function; the ultrasonic power is 300W and the frequency is 30kHz.

[0029] S2: Immerse the iridium oxide powder in acid solution, filter to remove insoluble impurities, add a precipitant to precipitate the iridium, and obtain the precipitate; The acid solution comprises hydrochloric acid and nitric acid in a volume ratio of 3:1, with the hydrochloric acid concentration being 10 wt% and the nitric acid concentration being 10 wt%, and the precipitant being ammonium chloride.

[0030] S3: After washing and drying, the precipitate is calcined and reduced with hydrogen to reduce iridium oxide to metallic iridium powder.

[0031] Example 4 A method for extracting metallic iridium from an iridium-titanium anode plate includes the following steps: S1: Peel off the coating of the iridium-titanium anode plate to obtain iridium oxide powder; The peeling method is as follows: The iridium-titanium anode plate was immersed in a treatment solution, then frozen at -45°C for 25 minutes, followed by heating to 90°C and holding at that temperature for 15 minutes. This freezing-heating cycle was repeated 10 times. Finally, a film-forming agent containing microorganisms was sprayed onto the surface of the iridium-titanium anode plate; the microorganisms were *Synthobacterium violaceum* (Chroma violaceum). C.violaceum The film-forming agent is a chitosan solution with a concentration of 5 wt%, and microorganisms account for 60% of the mass of the film-forming agent.

[0032] The treatment solution comprises methyl isobutyl ketone, furanone, a surfactant, and water in a mass ratio of 40:15:3:50; the surfactant is a fatty alcohol polyoxyethylene ether.

[0033] When maintaining the temperature, activate the ultrasonic function; the ultrasonic power is 350W and the frequency is 25kHz.

[0034] S2: Immerse the iridium oxide powder in acid solution, filter to remove insoluble impurities, add a precipitant to precipitate the iridium, and obtain the precipitate; The acid solution comprises hydrochloric acid and nitric acid in a volume ratio of 3:1, with the hydrochloric acid concentration being 10 wt% and the nitric acid concentration being 10 wt%, and the precipitant being ammonium chloride.

[0035] S3: After washing and drying, the precipitate is calcined and reduced with hydrogen to reduce iridium oxide to metallic iridium powder.

[0036] Example 5 A method for extracting metallic iridium from an iridium-titanium anode plate includes the following steps: S1: Peel off the coating of the iridium-titanium anode plate to obtain iridium oxide powder; The peeling method is as follows: The iridium-titanium anode plate was immersed in a treatment solution, then frozen at -45°C for 25 minutes, followed by heating to 90°C and holding at that temperature for 15 minutes. This freezing-heating cycle was repeated 10 times. Finally, a film-forming agent containing microorganisms was sprayed onto the surface of the iridium-titanium anode plate; the microorganisms were *Synthobacterium violaceum* (Chroma violaceum). C.violaceum The film-forming agent is a chitosan solution with a concentration of 5 wt%, and microorganisms account for 60% of the mass of the film-forming agent.

[0037] The treatment solution comprises methyl isobutyl ketone, furanone, a surfactant, and water in a mass ratio of 60:18:2.5:40; the surfactant is a fatty alcohol polyoxyethylene ether.

[0038] When maintaining the temperature, activate the ultrasonic function; the ultrasonic power is 400W and the frequency is 30kHz.

[0039] S2: Immerse the iridium oxide powder in acid solution, filter to remove insoluble impurities, add a precipitant to precipitate the iridium, and obtain the precipitate; The acid solution comprises hydrochloric acid and nitric acid in a volume ratio of 3:1, with the hydrochloric acid concentration being 10 wt% and the nitric acid concentration being 10 wt%, and the precipitant being ammonium chloride.

[0040] S3: After washing and drying, the precipitate is calcined and reduced with hydrogen to reduce iridium oxide to metallic iridium powder.

[0041] Comparative Example 1 Unlike Example 1, furanone was not added to the treatment solution in the stripping method; otherwise, the process was the same as in Example 1.

[0042] Comparative Example 2 Unlike Example 1, the stripping method did not involve freeze-thaw treatment. Instead, the iridium-titanium anode plate was immersed in a treatment solution, and then a film-forming agent containing microorganisms was sprayed onto the surface of the iridium-titanium anode plate. The rest was the same as in Example 1.

[0043] Comparative Example 3 Unlike Example 1, the stripping method did not involve spraying a film-forming agent containing microorganisms onto the surface of the iridium-titanium anode plate; otherwise, it was the same as in Example 1.

[0044] The performance of the above embodiments and comparative examples was tested, and the test results are shown in Table 1.

[0045] Table 1 Performance test results of the examples and comparative examples

[0046] As shown in Table 1, the performance of the embodiment is superior to that of the comparative example. The main reason is that the present invention first immerses the iridium-titanium anode plate in the treatment solution, causing the organic matter inside to swell. Then, repeated freeze-thaw cycles cause the coating to become porous under stress and water molecule volume changes. Combined with the positive tropism of microorganisms and furanones, microorganisms quickly enter the porous channels to the polymer surface, prompting them to secrete extracellular enzymes, accelerating the swelling and fracture of the material, and accelerating the peeling of the coating on the iridium-titanium anode plate; thereby reducing iridium loss and improving iridium recovery rate.

[0047] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A method for extracting metallic iridium from an iridium-titanium anode plate, characterized in that, Includes the following steps: S1: Peel off the coating of the iridium-titanium anode plate to obtain iridium oxide powder; The peeling method is as follows: Immerse the iridium-titanium anode plate in the treatment solution, then freeze it at -40°C to -50°C for 10-30 minutes, then raise the temperature to 70-90°C and hold it for 10-20 minutes. Repeat the freezing-heating cycle 3-10 times. Finally, spray a film-forming agent containing microorganisms onto the surface of the iridium-titanium anode plate. The treatment solution includes methyl isobutyl ketone, furanone, surfactant, and water; S2: Immerse the iridium oxide powder in acid solution, filter to remove insoluble impurities, add a precipitant to precipitate the iridium, and obtain the precipitate; S3: After washing and drying, the precipitate is calcined and reduced with hydrogen to reduce iridium oxide to metallic iridium powder.

2. The method for extracting metallic iridium from an iridium-titanium anode plate according to claim 1, characterized in that, In step S1, during the heat preservation process, the ultrasound is activated.

3. The method for extracting metallic iridium from an iridium-titanium anode plate according to claim 2, characterized in that, In step S1, the ultrasonic power is 300-400W and the frequency is 20-30kHz.

4. The method for extracting metallic iridium from an iridium-titanium anode plate according to claim 1, characterized in that, In step S1, the mass ratio of methyl isobutyl ketone, furanone, surfactant and water is 40-60:10-20:1-3:30-50.

5. The method for extracting metallic iridium from an iridium-titanium anode plate according to claim 4, characterized in that, In step S1, the surfactant is a fatty alcohol polyoxyethylene ether.

6. The method for extracting metallic iridium from an iridium-titanium anode plate according to claim 4, characterized in that, In step S1, the microorganism is Chromobacterium violaceum.

7. The method for extracting metallic iridium from an iridium-titanium anode plate according to claim 4, characterized in that, The film-forming agent is a polyvinyl alcohol solution or a chitosan solution.

8. The method for extracting metallic iridium from an iridium-titanium anode plate according to claim 1, characterized in that, The acid solution includes hydrochloric acid and nitric acid, and the precipitant is ammonium chloride.

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