A method for recovering high purity iridium powder from iridium residue targets and machining waste therefrom

Abstract

The application discloses a method for recovering and preparing high-purity iridium powder from iridium residual targets and machining waste thereof, and comprises the following steps: (1) pretreatment of the iridium residual targets and machining waste thereof; (2) mixed alkali liquefaction; (3) oxidation liquid preparation; (4) selective crystallization; (5) thermal decomposition + high-temperature hydrogen atmosphere deoxidation; and (6) acid boiling impurity removal. Through the method, high-purity iridium powder can be recovered and purified from the iridium residual targets and machining waste thereof, the powder has a particle size less than 5 microns, a purity greater than 99.999%, and good powder uniformity, and can be used as an iridium sputtering target material for information storage.

Description

Technical Field

[0001] This invention belongs to the field of precious metal recycling, specifically relating to a method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste. Background Technology

[0002] Iridium sputtering targets are high-value-added specialty electronic products and key materials used in semiconductor memory, microelectromechanical systems (MEMS), and antiferromagnetic spin devices. Iridium thin films can be fabricated using physical vapor deposition methods such as magnetron sputtering. They are primarily used as oxygen barrier materials in CMOS capacitors, electrode layers in MEMS, and antiferromagnetic pinning layers in magnetoelectronic devices, with significant application demand. However, during magnetron sputtering, the target utilization rate is only 30%-70%, and due to the low-temperature brittleness of iridium, a large amount of processing waste is generated during iridium target processing. Therefore, the recycling and reuse of residual iridium targets and processing waste is of great importance.

[0003] Iridium is chemically stable and extremely corrosion-resistant, making it the most difficult platinum group metal to dissolve. Currently, alkali melting pretreatment is typically used for powdered or granular iridium-containing catalysts and compounds, while alloying activation pretreatment is usually employed to dissolve iridium in iridium alloy waste. Iridium purification and refining usually take place in a solution system, and separation is quite challenging. A common method is repeated precipitation with ammonium chloroiridate, combined with methods such as sulfidation, sodium nitrite complexation, solvent extraction, and ion exchange, depending on the raw material properties, to separate noble and base metal impurities from the iridium solution, obtaining a pure iridium solution. Finally, qualified iridium powder is prepared through ammonium chloride precipitation, calcination, and hydrogen reduction.

[0004] CN108421986A discloses a method for separating and purifying iridium trichloride to prepare high-purity iridium powder. This method uses sodium nitrite and ammonium chloride as precipitants, and obtains iridium powder with a purity greater than 99.999% through a process involving reduction-precipitation-redissolution-reprecipitation-calcination-reduction. However, this method has a long process flow and does not involve the recycling and purification of iridium waste.

[0005] CN108658133A discloses a rapid dissolution method for the refractory metal iridium, which uses iridium powder and hydrochloric acid to dissolve iridium by passing chlorine gas through it. Although the process is simple, it uses a large amount of toxic chlorine gas, which increases the pressure on environmental remediation.

[0006] CN101985696A discloses a method for extracting iridium from iridium-containing materials. The method involves dissolving the iridium in hydrochloric acid, oxidizing it with nitric acid, precipitating it with ammonium chloride, and removing impurities with hydrazine hydrate to obtain purified (NH4)2IrCl6 crystals. These crystals are then calcined and reduced to obtain iridium powder with a purity of 99.98%. This method achieves the separation and removal of impurities from the iridium powder, but the purity of the resulting iridium powder is not high.

[0007] CN113477939A discloses a method for preparing high-purity iridium powder, mainly involving a method for separating and purifying iridium from materials containing impurities such as rhodium, platinum, and iron. The method includes steps such as crushing, dissolving, oxidation-reduction, reduction to remove impurities, oxidation precipitation, and calcination-reduction to obtain 99.999% high-purity iridium powder. However, this method involves numerous steps and does not achieve control over the morphology and particle size of the iridium powder. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste includes:

[0011] (1) Pretreatment of iridium target waste and its machining waste: Immerse the iridium target waste and its machining waste in organic solvents such as ethanol or acetone, then place them in an ultrasonic cleaner for ultrasonic cleaning, filter and dry to remove surface oil stains, then crush the iridium target waste and its machining waste into powder, soak them thoroughly in dilute acid solution, filter and wash them with ultrapure water until neutral, and then dry them for later use.

[0012] (2) Liquefaction of mixed alkali: The pretreated iridium target residue and machining waste are mixed with mixed alkali in proportion, transferred to a calcining furnace for calcination, cooled with the furnace after calcination, taken out, and thoroughly soaked and washed in heated ultrapure water, then filtered for later use.

[0013] (3) Oxidation to produce liquid: The filter residue is transferred to an acidic reaction vessel, hydrochloric acid solution is added in proportion to dissolve it, hydrogen peroxide is added to fully oxidize it, and then filtered. The filtrate is taken for later use.

[0014] (4) Selective crystallization: The filtrate is transferred into the reaction vessel, and crystallization reagent and surfactant are added under stirring. After the reaction is complete at room temperature, the mixture is filtered, washed with ultrapure water until neutral, and then dried for later use.

[0015] (5) Thermal decomposition + high-temperature hydrogen atmosphere deoxygenation: The dried iridium-containing material is transferred into a tube furnace for thermal decomposition reaction. After complete thermal decomposition, nitrogen gas is introduced first and then hydrogen gas is introduced for deoxygenation treatment.

[0016] (6) Acid boiling to remove impurities: The deoxidized iridium powder is soaked and washed thoroughly in a heated mixed acid solution, washed with ultrapure water until neutral, and then dried to obtain high-purity iridium powder.

[0017] Further, in step (1), the dilute acid solution is any one or more of analytical grade hydrochloric acid, nitric acid, and sulfuric acid with a concentration of 10-30%; the soaking temperature is 60-100℃ and the soaking time is 30-150min.

[0018] Further, in step (2), the mixed alkali is potassium hydroxide and potassium peroxide, with a mass ratio of 1:1 to 1:3, a calcination temperature of 550-750℃, a calcination time of 1-3h, a pure water soaking temperature of 60-100℃, and a soaking time of 2-6h.

[0019] Furthermore, in step (3), the concentration of hydrochloric acid solution is 10-30%, the solid-liquid ratio is 1:1-1:5, and the ratio of hydrogen peroxide to iridium is 1:2-1:5.

[0020] Further, in step (4), the crystallization agent is any one or more of ammonium bisulfate, ammonium nitrate, and ammonium bromide, and the mass ratio of the crystallization agent to iridium is 1:1-3:1; the nonionic surfactant is any one or more of PVA, PEG, and NPAM, the surfactant concentration is 5-30%, the reaction temperature is room temperature, and the reaction time is 1-3h.

[0021] Furthermore, in step (5), the thermal decomposition temperature is 500-800℃, the decomposition time is 2-5h, the deoxidation temperature is 600-750℃, and the deoxidation time is 1.5-3h.

[0022] Further, in step (6), the mixed acid solution is any of the following: high-purity hydrochloric acid, nitric acid, hydrofluoric acid, and sulfuric acid. The mixed acid solution is prepared with ultrapure water at a concentration of 10-30%, heated at 70-100℃, soaked for 1-3 hours, washed until neutral, and then dried at 100-120℃.

[0023] The beneficial effects of this invention are:

[0024] This invention relates to a method for preparing high-purity iridium powder by recycling iridium targets and their processing waste. The purity of the iridium powder can reach 99.999%. At the same time, a dispersant is innovatively introduced during the crystallization process to achieve controllable preparation of the iridium powder morphology. Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope image of the high-purity iridium powder obtained in Example 1 of the present invention.

[0026] Figure 2 This is a scanning electron microscope image of the high-purity iridium powder obtained in Example 2 of the present invention.

[0027] Figure 3 This is a scanning electron microscope image of the high-purity iridium powder obtained in Example 3 of the present invention. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this is not intended to limit the invention in any way. Any changes or modifications made based on the technical concept of the present invention shall fall within the protection scope of the present invention.

[0029] A method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste includes:

[0030] (1) Pretreatment of iridium target waste and its machining waste: Immerse the iridium target waste and its machining waste in organic solvents such as ethanol or acetone, then place them in an ultrasonic cleaner for ultrasonic cleaning, filter and dry to remove surface oil stains, then crush the iridium target waste and its machining waste into powder, soak them thoroughly in dilute acid solution, filter and wash them with ultrapure water until neutral, and then dry them for later use.

[0031] (2) Liquefaction of mixed alkali: The pretreated iridium target residue and machining waste are mixed with mixed alkali in proportion, transferred to a calcining furnace for calcination, cooled with the furnace after calcination, taken out, and thoroughly soaked and washed in heated ultrapure water, then filtered for later use.

[0032] (3) Oxidation to produce liquid: The filter residue is transferred to an acidic reaction vessel, hydrochloric acid solution is added in proportion to dissolve it, hydrogen peroxide is added to fully oxidize it, and then filtered. The filtrate is taken for later use.

[0033] (4) Selective crystallization: The filtrate is transferred into a reaction vessel, and crystallization reagent and surfactant are added under stirring. After the reaction is complete at room temperature, the mixture is filtered, washed with ultrapure water until neutral, and then dried for later use.

[0034] (5) Thermal decomposition + high-temperature hydrogen atmosphere deoxygenation: The dried iridium-containing material is transferred into a tube furnace for thermal decomposition reaction. After complete thermal decomposition, nitrogen gas is introduced first and then hydrogen gas is introduced for deoxygenation treatment.

[0035] (6) Acid boiling to remove impurities: The deoxidized iridium powder is soaked and washed thoroughly in a heated mixed acid solution, washed with ultrapure water until neutral, and then dried to obtain high-purity iridium powder.

[0036] The dilute acid solution in step (1) is any one or more of analytical grade hydrochloric acid, nitric acid, and sulfuric acid with a concentration of 10-30%; the soaking temperature is 60-100℃ and the soaking time is 30-150 mins.

[0037] The alkali mixture in step (2) is potassium hydroxide and potassium peroxide in a mass ratio of 1:1 to 1:3. The calcination temperature is 550-750℃ and the calcination time is 1-3h. The pure water soaking temperature is 60-100℃ and the soaking time is 2-6h.

[0038] In step (3), the concentration of hydrochloric acid solution is 10-30%, the solid-liquid ratio is 1:1-1:5, and the ratio of hydrogen peroxide to iridium is 1:2-1:5.

[0039] In step (4), the crystallization agent is any one or more of ammonium bisulfate, ammonium nitrate, and ammonium bromide, and the mass ratio of the crystallization agent to iridium is 1:1-3:1; the nonionic surfactant is any one or more of PVA, PEG, and NPAM, the surfactant concentration is 5-30%, the reaction temperature is room temperature, and the reaction time is 1-3h.

[0040] The thermal decomposition temperature of step (5) is 500-800℃, the decomposition time is 2-5h, the deoxidation temperature is 600-750℃, and the deoxidation time is 1.5-3h.

[0041] The mixed acid solution in step (6) is any of the following: high-purity hydrochloric acid, nitric acid, hydrofluoric acid, and sulfuric acid. The mixed acid solution is prepared with ultrapure water at a concentration of 10-30%, heated at 70-100℃, soaked for 1-3 hours, and dried at 100-120℃ after being washed until neutral.

[0042] Example 1

[0043] (1) Pretreatment of iridium target waste and its machining waste: Immerse the iridium target waste and its machining waste in organic solvents such as ethanol or acetone, then place them in an ultrasonic cleaner for ultrasonic cleaning, filter and dry to remove surface oil stains, then crush the iridium target waste and its machining waste into powder, soak them in 10% dilute hydrochloric acid solution at 80℃ for 60 mins, filter and wash with ultrapure water until neutral, and then dry for later use.

[0044] (2) Liquefaction of mixed alkali: Mixed alkali is prepared with potassium hydroxide and potassium peroxide in a mass ratio of 1:1. The pretreated iridium target residue and machining waste are mixed with the mixed alkali and transferred to a calcining furnace for calcination at 550°C for 2 hours. After calcination, the mixture is cooled with the furnace and taken out. It is then soaked and washed in 60°C ultrapure water for 4 hours and filtered for later use.

[0045] (3) Oxidation to produce liquid: The filter residue is transferred to an acidic reactor, and a 20% hydrochloric acid solution is added at a solid-liquid ratio of 1:3 to dissolve it. Hydrogen peroxide is added at a hydrogen peroxide to iridium ratio of 1:2 to fully oxidize the solution and then filter it. The filtrate is then used for later use.

[0046] (4) Selective crystallization: The filtrate is transferred into a reaction vessel, and ammonium bisulfate and ammonium nitrate are added as crystallization reagents under stirring conditions. The mass ratio of crystallization reagent to iridium is 1:1. PEG with a concentration of 20% is added as a surfactant. After reacting at room temperature for 2 hours, the mixture is filtered, washed with ultrapure water until neutral, and then dried for later use.

[0047] (5) Thermal decomposition + high-temperature hydrogen atmosphere deoxygenation: The dried iridium-containing material is transferred to a tube furnace and thermally decomposed at 650°C for 3 hours. Then, nitrogen gas is introduced first and then hydrogen gas is introduced, and deoxygenation is carried out at 650°C for 2 hours.

[0048] (6) Acid boiling to remove impurities: Prepare a mixed acid solution of hydrochloric acid, nitric acid and hydrofluoric acid, dilute it with ultrapure water to a concentration of 10%, and heat it to 90°C. Soak and wash the deoxygenated iridium powder in the heated mixed acid solution for 2 hours, wash it with ultrapure water until neutral, and then dry it at 120°C to obtain high-purity iridium powder.

[0049] Example 2

[0050] (1) Pretreatment of iridium target waste and its machining waste: Immerse the iridium target waste and its machining waste in organic solvents such as ethanol or acetone, then place them in an ultrasonic cleaner for ultrasonic cleaning, filter and dry to remove surface oil stains, then crush the iridium target waste and its machining waste into powder, soak them in 20% dilute nitric acid solution at 90℃ for 90 mins, filter and wash with ultrapure water until neutral, and then dry for later use.

[0051] (2) Liquefaction of mixed alkali: Mixed alkali is prepared with potassium hydroxide and potassium peroxide in a mass ratio of 1:2. The pretreated iridium target residue and machining waste are mixed with the mixed alkali and transferred to a calcining furnace for calcination at 650°C for 3 hours. After calcination, the mixture is cooled with the furnace and taken out. It is then soaked and washed in 80°C ultrapure water for 3 hours and filtered for later use.

[0052] (3) Oxidation to produce liquid: The filter residue is transferred to an acidic reactor, and a 30% hydrochloric acid solution is added at a solid-liquid ratio of 1:2 to dissolve it. Hydrogen peroxide is added at a hydrogen peroxide to iridium ratio of 1:3 to fully oxidize the solution and then filtered. The filtrate is then used for later use.

[0053] (4) Selective crystallization: The filtrate is transferred into the reaction vessel, and ammonium bromide and ammonium nitrate are added as crystallization reagents under stirring conditions. The mass ratio of crystallization reagent to iridium is 2:1. PVA with a concentration of 15% is added as a surfactant. After reacting at room temperature for 3 hours, the mixture is filtered, washed with ultrapure water until neutral, and then dried for later use.

[0054] (5) Thermal decomposition + high-temperature hydrogen atmosphere deoxygenation: The dried iridium-containing material is transferred to a tube furnace and thermally decomposed at 750°C for 2 hours. Then, nitrogen gas is introduced first and then hydrogen gas is introduced, and deoxygenation is carried out at 750°C for 1.5 hours.

[0055] (6) Acid boiling to remove impurities: Prepare a mixed acid solution of sulfuric acid, nitric acid and hydrofluoric acid, dilute it with ultrapure water to a concentration of 20%, and heat it to 100°C. Soak and wash the deoxygenated iridium powder in the heated mixed acid solution for 1 hour, wash it with ultrapure water until neutral, and then dry it at 100°C to obtain high-purity iridium powder.

[0056] Example 3

[0057] (1) Pretreatment of iridium target waste and its machining waste: Immerse the iridium target waste and its machining waste in organic solvents such as ethanol or acetone, then place them in an ultrasonic cleaner for ultrasonic cleaning, filter and dry to remove surface oil stains, then crush the iridium target waste and its machining waste into powder, soak them in 30% dilute sulfuric acid solution at 100℃ for 120 mins, filter and wash with ultrapure water until neutral, and then dry for later use.

[0058] (2) Liquefaction of mixed alkali: Mixed alkali is prepared with potassium hydroxide and potassium peroxide in a mass ratio of 1:1. The pretreated iridium target residue and machining waste are mixed with the mixed alkali and transferred to a calcining furnace for calcination at 750°C for 1.5 hours. After calcination, the mixture is cooled with the furnace and taken out. It is then soaked and washed in 100°C ultrapure water for 4 hours and filtered for later use.

[0059] (3) Oxidation to produce liquid: The filter residue is transferred to an acidic reactor, and a 30% hydrochloric acid solution is added at a solid-liquid ratio of 1:5 to dissolve it. Hydrogen peroxide is added at a hydrogen peroxide to iridium ratio of 1:5 to fully oxidize the solution and then filtered. The filtrate is then used for later use.

[0060] (4) Selective crystallization: The filtrate is transferred into the reaction vessel, and ammonium bromide is added as a crystallization agent under stirring. The mass ratio of the crystallization agent to iridium is 3:1. NPAM with a concentration of 30% is added as a surfactant. After reacting at room temperature for 3 hours, the mixture is filtered, washed with ultrapure water until neutral, and then dried for later use.

[0061] (5) Thermal decomposition + high-temperature hydrogen atmosphere deoxygenation: The dried iridium-containing material is transferred to a tube furnace and thermally decomposed at 550°C for 5 hours. Then, nitrogen gas is introduced first, followed by hydrogen gas, and deoxygenation is carried out at 600°C for 3 hours.

[0062] (6) Acid boiling to remove impurities: Prepare a mixed acid solution of hydrochloric acid, sulfuric acid and hydrofluoric acid, dilute it with ultrapure water to a concentration of 30%, and heat it to 100°C. Soak and wash the deoxygenated iridium powder in the heated mixed acid solution for 1.5 hours, wash it with ultrapure water until neutral, and then dry it at 110°C to obtain high-purity iridium powder.

[0063] The high-purity iridium powder prepared in the embodiments of the present invention was analyzed by glow discharge mass spectrometry, and the results are shown in Table 1:

[0064] Table 1. Impurity Analysis Results of High-Purity Iridium Powder by Glow Discharge Mass Spectrometry

[0065]

[0066]

[0067] As can be seen from the accompanying drawings and Table 1, the present invention recovers and purifies high-purity iridium powder with a particle size of less than 5 μm, a purity of more than 99.999%, and good powder uniformity, which can be used as raw material for iridium sputtering targets for information storage.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste, characterized in that, The method specifically includes the following steps: (1) Pretreatment of iridium target waste and its machining waste: Immerse the iridium target waste and its machining waste in an organic solvent, then place it in an ultrasonic cleaner, ultrasonically clean it, filter and dry it to remove surface oil stains, then crush it into powder, soak it thoroughly in a dilute acid solution, filter it, wash it with ultrapure water until neutral, and then dry it for later use. (2) Liquefaction of mixed alkali: The pretreated iridium target residue and machining waste are mixed with mixed alkali in proportion, transferred to a calcining furnace for calcination, cooled with the furnace after calcination, taken out, and thoroughly soaked and washed in heated ultrapure water, then filtered for later use. (3) Oxidation to produce liquid; the filter residue is transferred to an acidic reaction vessel, hydrochloric acid solution is added in proportion to dissolve it, hydrogen peroxide is added to fully oxidize it, and then filtered. The filtrate is taken for later use. (4) Selective crystallization: The filtrate is transferred into the reaction vessel, and crystallization reagent and surfactant are added under stirring. After the reaction is complete at room temperature, the mixture is filtered, washed with ultrapure water until neutral, and then dried for later use. (5) Thermal decomposition + high-temperature hydrogen atmosphere deoxygenation: The dried iridium-containing material is transferred into a tube furnace for thermal decomposition reaction. After complete thermal decomposition, nitrogen gas is first introduced and then hydrogen gas is introduced for deoxygenation treatment. (6) Acid boiling to remove impurities: The deoxidized iridium powder is immersed and washed thoroughly in a heated mixed acid solution, washed with ultrapure water until neutral, and then dried to obtain high-purity iridium powder; the iridium powder has a particle size of less than 5 μm and a purity of greater than 99.999%.

2. The method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste as described in claim 1, characterized in that, The dilute acid solution in step (1) is any one or more of analytical grade hydrochloric acid, nitric acid, and sulfuric acid with a concentration of 10-30%; the soaking temperature is 60-100℃ and the soaking time is 30-150min.

3. The method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste as described in claim 1, characterized in that, The mixed alkali in step (2) is potassium hydroxide and potassium peroxide, with a mass ratio of 1:1 to 1:3, a calcination temperature of 550-750℃, and a calcination time of 1-3h.

4. The method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste as described in claim 1, characterized in that, In step (2), the pure water immersion temperature is 60-100℃ and the immersion time is 2-6h.

5. The method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste as described in claim 1, characterized in that, The concentration of the hydrochloric acid solution in step (3) is 10-30%, and the solid-liquid ratio is 1:1-1:

5.

6. The method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste as described in claim 1, characterized in that, In step (3), the ratio of hydrogen peroxide to iridium is 1:2 to 1:

5.

7. The method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste as described in claim 1, characterized in that, The crystallization reagent in step (4) is any one or more of ammonium bisulfate, ammonium nitrate, and ammonium bromide; the mass ratio of the crystallization reagent to iridium is 1:1-3:

1.

8. The method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste as described in claim 1, characterized in that, In step (4), the nonionic surfactant used is any one or more of PVA, PEG, and NPAM; the surfactant concentration is 5-30%, the reaction temperature is room temperature, and the reaction time is 1-3h.

9. The method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste as described in claim 1, characterized in that, The thermal decomposition temperature in step (5) is 500-800℃, the decomposition time is 2-5h, the deoxidation temperature is 600-750℃, and the deoxidation time is 1.5-3h.

10. The method for recovering and preparing high-purity iridium powder from iridium target residues and their machining waste as described in claim 1, characterized in that, The mixed acid solution in step (6) is any of the following: high-purity hydrochloric acid, nitric acid, hydrofluoric acid, and sulfuric acid. The mixed acid solution is prepared with ultrapure water at a concentration of 10-30%, heated at 70-100℃, soaked for 1-3 hours, and dried at 100-120℃ after being washed to neutral.

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