A method for extracting and recovering rare precious metal iridium from metal molten salt

Abstract

The invention discloses a method for extracting and recovering rare and precious metal iridium from a molten metal salt, belonging to the technical field of iridium metal recovery. The method comprises the following steps: placing the molten metal salt into a reaction vessel, adding distilled water, heating and stirring, cooling and standing, then adding CsCl, stirring and standing, adding a hydrochloric acid solution to adjust the pH value to 2-3, causing the iridium salt in the molten metal salt to react to obtain Cs2IrCl6, the Cs2IrCl6 being dried and placed into a reaction vessel, then adding Na2CO3 and distilled water, heating and stirring, adding a NaOH solution to adjust the pH value to 10-12, obtaining iridium oxide hydrate, drying and grinding into powder, placing the powder into an ultra-high pressure reactor, evacuating and passing argon gas to wash the chamber, then placing ultra-pure hydrogen, heating and heat-insulating, then cooling, and discharging the gas in the reactor to obtain iridium powder. The method has a simple operation process, can extract and recover the iridium metal from the molten metal salt, and thus reduces waste of the iridium metal.

Description

Technical Field

[0001] The invention belongs to the technical field of metal iridium recovery, and particularly relates to a method for extracting and recovering rare and precious metal iridium from metal molten salt. Background Art

[0002] Iridium metal has excellent physical and chemical properties in the rare metal system. It has strong chemical stability and corrosion resistance. Its melting point is 2440℃. It can maintain excellent thermal strength, thermal stability and mechanical properties at high temperatures. When the temperature is as high as 2100-2200℃, its oxygen permeability is 10 -14 g.cm -1 .s -1 It has excellent high-temperature antioxidant properties and is an excellent high-temperature oxygen diffusion barrier material. It is widely used in microelectronics, electrode materials, optoelectronic materials, fuel cells, gas sensors, aerospace and other high-tech and military technology fields.

[0003] Iridium metal coating is currently the only successfully tested anti-oxidation coating that can be used above 1800°C. It is widely used in structural parts or products that withstand ultra-high temperatures. It can greatly improve the high-temperature anti-oxidation performance and service life of the products. However, iridium metal is hard and brittle, has a high melting point, and is expensive, making it difficult to prepare using conventional casting and machining methods. There are currently three main methods for preparing iridium coatings, among which molten salt electrodeposition is a method with greater application value. When preparing the iridium coating, the molten salt is an iridium-containing metal molten salt. The iridium metal coating prepared using the iridium-containing metal molten salt is currently the most excellent anti-oxidation coating. After the iridium metal coating is prepared using the iridium-containing metal molten salt, a certain amount of iridium salt will still remain in the remaining metal molten salt. The existing technology is to treat the metal molten salt after the iridium metal coating is prepared as solid waste, but this will cause a waste of iridium metal.

[0004] Therefore, the current technical problem to be solved is to extract, recycle and reuse metallic iridium from metal molten salt and reduce the waste of metallic iridium. Summary of the Invention

[0005] The object of the present invention is to provide a method for extracting and recycling the rare and precious metal iridium from a metal molten salt, thereby reducing the problem of waste of the metal iridium.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for extracting and recovering rare precious metal iridium from a molten metal salt comprises the following steps:

[0008] The first step is to weigh the molten metal salt, place it in a mixing reaction vessel, add distilled water, heat to 100 ° C, stir with ultrasonic vibration for 0.5-1h, cool to room temperature and let it stand for 1-2h, then add CsCl, stir with ultrasonic vibration for 15-30min, let it stand for 1-2h, add hydrochloric acid solution to adjust the pH value to 2-3, filter and wash to obtain Cs2IrCl6, and dry the Cs2IrCl6 to obtain solid A, which is reddish brown;

[0009] The second step is to place solid A in a constant temperature heating reaction vessel, add Na2CO3 and distilled water, heat the temperature to 60-80°C, and stir with ultrasonic vibration for 0.5-1h. After solid A changes from reddish brown to blue-black, heat it to 100°C; continue ultrasonic vibration stirring for 0.5-1h, stop stirring, add NaOH solution to adjust the pH value to 10-12, keep warm for 1-2h, cool to room temperature, filter with filter paper, wash with distilled water to obtain iridium oxide hydrate, dry it to obtain solid B, and grind it into powder to obtain solid powder;

[0010] The third step is to place the solid powder obtained in the second step into an ultra-high pressure reactor, evacuate the chamber, purge the chamber with argon, and then introduce ultra-pure hydrogen until the pressure in the reactor reaches 10-12 MPa. Stop charging, turn on the heating device, raise the temperature to 800-1000°C, and keep the temperature for 24-48 hours. After cooling to room temperature, discharge the gas in the reactor, open the furnace to obtain iridium powder, collect the iridium powder in a dust-free plastic bag, and vacuum pack it.

[0011] Furthermore, the metal molten salt in the first step refers to the molten salt tailings remaining after the iridium coating is prepared using the iridium-containing metal molten salt.

[0012] Furthermore, in the first step, the mass ratio of the metal molten salt to distilled water and CsCl is 20:60:1.

[0013] Furthermore, the mass fraction of the hydrochloric acid solution in the first step is 15%.

[0014] Furthermore, the drying condition in the first step is drying at 150-200° C. for 1-2 hours.

[0015] Furthermore, in the second step, the mass ratio of solid A to Na2CO3 is 2:1.

[0016] Furthermore, in the second step, the amount of distilled water used is 10 times the total mass of solid A and Na2CO3.

[0017] Furthermore, the mass fraction of the NaOH solution added in the second step is 30%.

[0018] Furthermore, the drying condition in the second step is drying at 300° C. for 1-2 hours.

[0019] Furthermore, the ultrapure hydrogen standard in the third step is that the purity of the hydrogen is not less than 99.9999%.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides a method for extracting and recovering rare and precious metal iridium from a metal molten salt. The method comprises the following steps: placing the metal molten salt in a reaction vessel and adding distilled water, boiling and stirring the molten salt, cooling and standing the molten salt, then adding CsCl, stirring and standing the molten salt, and adjusting the solution to an acidic environment. The iridium salt in the metal molten salt reacts to obtain a reddish-brown precipitate Cs2IrCl6. After drying the Cs2IrCl6, Na2CO3 and distilled water are added to the molten salt, heating and ultrasonically vibrating and stirring the precipitate. After stopping the vibration and stirring, NaOH solution is added to adjust the pH value to obtain a blue-black solid iridium oxide hydrate. Iridium oxide hydrate is dried and then ground into powder, which is then placed in an ultra-high pressure reactor. The reactor is vacuumed and argon is passed through to clean the chamber. Ultra-pure hydrogen is placed in the reactor and then heated and kept warm. After the heat preservation is completed, the reactor is cooled to room temperature, the gas in the reactor is discharged, and the furnace is opened to obtain iridium powder. The method has a simple operation process, a short extraction cycle, simple and easy-to-obtain materials required in the extraction process, low extraction cost, and can efficiently extract the rare and precious metal iridium from the metal molten salt for recycling and reuse, thereby reducing waste of the metal iridium. The recovery rate is greater than 98%, and the purity of the recovered metal iridium reaches more than 99%. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] Example 1

[0024] A method for extracting and recovering rare precious metal iridium from a molten metal salt comprises the following steps:

[0025] The first step is to weigh 3 kg of molten metal salt and place it in a mixed reaction container, add 9 kg of distilled water in a ratio of 1:3 between the mass ratio of molten metal salt and distilled water, heat to 100 ° C, stir with ultrasonic vibration for 40 minutes, cool to room temperature, and let it stand for 1 hour, add 150 g of CsCl in a ratio of 20:1 between the mass ratio of molten metal salt and CsCl, stir with ultrasonic vibration for 15 minutes, let it stand for 1 hour, add 15% hydrochloric acid solution to adjust the pH value to 2, filter the solution with filter paper and wash it to obtain 240 g of Cs2IrCl6, and place the Cs2IrCl6 in a vacuum drying oven at 200 ° C for 1 hour to obtain solid A, which is reddish brown;

[0026] The second step is to place 240g of solid A obtained in the first step into a constant temperature heating reaction vessel, add 120g of Na2CO3 according to the mass ratio of solid A to Na2CO3 of 2:1, add 3.6kg of distilled water according to 10 times the total mass of solid A and Na2CO3, heat the solution temperature to 60°C, stir with ultrasonic vibration for 30min, and heat the solid A from reddish brown to bluish black, then raise the temperature to 100°C, continue stirring for 30min and stop stirring, add 30% NaOH solution with a mass fraction to adjust the pH value to 10, keep warm for 1h, cool to room temperature, filter with filter paper and wash with distilled water to obtain 161.4g of iridium oxide hydrate, put it into a vacuum drying oven at 300°C, dry and dehydrate it for 1h to obtain 80g of solid B, put solid B into a grinding device and grind it into powder, grind it for 3h, and mix it evenly in a mixer to obtain a solid powder;

[0027] The third step is to put the solid powder obtained in the second step into an ultra-high pressure reactor, evacuate the chamber, purge the chamber with argon, and then introduce ultra-pure hydrogen until the pressure in the reactor reaches 10 MPa. Stop charging, turn on the heating device, raise the temperature to 1000°C, keep the reaction temperature for 24 hours, cool to room temperature, discharge the gas in the reactor, open the furnace to obtain 67.62g of iridium powder, collect the iridium powder into a dust-free plastic bag, and vacuum pack it.

[0028] In summary, the metallic iridium in the first step (240g Cs2IrCl6 iridium salt) was converted entirely from molten metal salt, yielding a theoretical metallic iridium content of 68.67g. The final metallic iridium weight obtained in the third step was 67.62g, resulting in a practical recovery of 98.47% in this method. ICP analysis revealed a purity of 99.53% for the iridium powder obtained.

[0029] Example 2

[0030] A method for extracting and recovering rare precious metal iridium from a molten metal salt comprises the following steps:

[0031] The first step is to weigh 3 kg of molten metal salt and place it in a mixed reaction container, add 9 kg of distilled water in a ratio of 1:3 between the mass ratio of molten metal salt and distilled water, heat to 100 ° C, stir with ultrasonic vibration for 30 minutes, cool to room temperature, and let it stand for 1.5 hours. Add 150 g of CsCl in a ratio of 20:1 between the mass ratio of molten metal salt and CsCl, stir with ultrasonic vibration for 22 minutes, let it stand for 1.5 hours, add 15% hydrochloric acid solution to adjust the pH value to 2.5, filter the solution with filter paper and wash it to obtain 236 g of Cs2IrCl6, and place the Cs2IrCl6 in a vacuum drying oven at 170 ° C for 1.5 hours to obtain solid A, which is reddish brown;

[0032] The second step is to place 240g of solid A obtained in the first step into a constant temperature heating reaction vessel, add 118g of Na2CO3 according to the mass ratio of solid A to Na2CO3 of 2:1, add 3.54kg of distilled water according to 10 times the total mass of solid A and Na2CO3, heat the solution temperature to 70°C, stir with ultrasonic vibration for 45min, and heat the solid A from reddish brown to bluish black, then raise the temperature to 100°C, continue stirring for 45min and stop stirring, add 30% NaOH solution by mass fraction to adjust the pH value to 11, keep warm for 1.5h, cool to room temperature, filter with filter paper and wash with distilled water to obtain 158.7g of iridium oxide hydrate, put it into a vacuum drying oven at 300°C, dry and dehydrate it for 1h to obtain 77g of solid B, put solid B into a grinding device and grind it into powder, grind it for 3h, and mix it evenly in a mixer to obtain solid powder;

[0033] The third step is to put the solid powder obtained in the second step into an ultra-high pressure reactor, evacuate the chamber, purge the chamber with argon, and then introduce ultra-pure hydrogen until the pressure in the reactor reaches 11 MPa. Stop charging, turn on the heating device, raise the temperature to 900°C, keep the reaction temperature for 36 hours, cool to room temperature, discharge the gas in the reactor, open the furnace to obtain 67.4g of iridium powder, collect the iridium powder in a dust-free plastic bag, and vacuum pack it.

[0034] In summary, the metallic iridium in the first step gained 236gCs2IrCl6 iridium salt is all converted by metal molten salt, and the theoretical metallic iridium content is 68.67g. The metallic iridium weight finally obtained in the third step is 67.4g, so the actual recovery rate of metallic iridium in this method is 98.15%. Through ICP detection, the iridium powder purity obtained reaches 99.6%.

[0035] Example 3

[0036] A method for extracting and recovering rare precious metal iridium from a molten metal salt comprises the following steps:

[0037] The first step is to weigh 3 kg of molten metal salt and place it in a mixed reaction container, add 9 kg of distilled water in a ratio of 1:3 between the mass ratio of molten metal salt and distilled water, heat to 100 ° C, stir with ultrasonic vibration for 60 minutes, cool to room temperature, and let it stand for 2 hours. Add 150 g of CsCl in a ratio of 20:1 between the mass ratio of molten metal salt and CsCl, stir with ultrasonic vibration for 30 minutes, let it stand for 2 hours, add 15% hydrochloric acid solution to adjust the pH value to 3, filter the solution with filter paper and wash it to obtain 242 g of Cs2IrCl6, and place the Cs2IrCl6 in a vacuum drying oven at 150 ° C for 2 hours to obtain solid A, which is reddish brown;

[0038] The second step is to place 242g of solid A obtained in the first step into a constant temperature heating reaction vessel, add 121g of Na2CO3 according to the mass ratio of solid A to Na2CO3 of 2:1, add 3.63kg of distilled water according to 10 times the total mass of solid A and Na2CO3, heat the solution temperature to 80°C, stir with ultrasonic vibration for 60min, and heat the solid A from reddish brown to bluish black, then raise the temperature to 100°C, continue stirring for 60min and stop stirring, add 30% NaOH solution by mass fraction to adjust the pH value to 12, keep warm for 2h, cool to room temperature, filter with filter paper and wash with distilled water to obtain 162.8g of iridium oxide hydrate, put it into a vacuum drying oven at 300°C, dry and dehydrate it for 1h to obtain 79g of solid B, put solid B into a grinding device and grind it into powder, grind it for 3h, and mix it evenly in a mixer to obtain a solid powder;

[0039] The third step is to put the solid powder obtained in the second step into an ultra-high pressure reactor, evacuate the chamber, purge the chamber with argon, and then introduce ultra-pure hydrogen until the pressure in the reactor reaches 12 MPa. Stop charging, turn on the heating device, raise the temperature to 800°C, keep the reaction temperature for 48 hours, cool to room temperature, discharge the gas in the reactor, open the furnace to obtain 67.53g of iridium powder, collect the iridium powder into a dust-free plastic bag, and vacuum pack it.

[0040] In summary, the metallic iridium in the first step (242g Cs2IrCl6 iridium salt) was converted entirely from molten metal salt, yielding a theoretical metallic iridium content of 68.67g. The final metallic iridium weight obtained in the third step was 67.53g, resulting in a practical recovery of 98.34% in this method. ICP analysis revealed a purity of 99.5% for the iridium powder obtained.

[0041] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0042] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for extracting and recovering rare and precious metal iridium from metal molten salt, characterized in that: The following steps are involved: Step 1: Weigh the molten metal salt, add distilled water, heat to 100°C, stir with ultrasonic vibration for 0.5-1h, cool to room temperature and let stand for 1-2h, add CsCl, stir with ultrasonic vibration for 15-30min, let stand for 1-2h, add hydrochloric acid solution to adjust the pH to 2-3, filter, wash and dry to obtain solid A; The second step is to place solid A in a reaction vessel, add Na2CO3 and distilled water, stir under ultrasonic vibration at 60-80°C for 0.5-1h, heat to 100°C, stir under ultrasonic vibration for 0.5-1h, add NaOH solution to adjust the pH value to 10-12, keep warm for 1-2h, cool to room temperature, filter and wash to obtain iridium oxide hydrate, dry to obtain solid B and grind into powder to obtain solid powder; The third step is to place the solid powder into an ultra-high pressure reactor, evacuate the chamber, purge the chamber with argon, and introduce ultra-pure hydrogen. When the pressure in the reactor reaches 10-12 MPa, stop charging, heat it to 800-1000°C, keep it warm for 24-48 hours, cool it to room temperature, exhaust the gas in the reactor, and open the furnace to collect and recycle the iridium powder.

2. The method for extracting and recovering rare and precious metal iridium from a metal molten salt according to claim 1, characterized in that: The metal molten salt refers to the molten salt tailings remaining after the iridium coating is prepared using the iridium-containing metal molten salt.

3. The method for extracting and recovering rare and precious metal iridium from a metal molten salt according to claim 1, characterized in that: In the first step, the mass ratio of the metal molten salt to distilled water and CsCl is 20:60:

1.

4. The method for extracting and recovering rare and precious metal iridium from a metal molten salt according to claim 1, characterized in that: In the second step, the mass ratio of solid A to Na2CO3 is 2:

1.

5. The method for extracting and recovering rare and precious metal iridium from a metal molten salt according to claim 1, characterized in that: The amount of distilled water used in the second step is 10 times the total mass of solid A and Na2CO3.

6. The method for extracting and recovering rare and precious metal iridium from a metal molten salt according to claim 1, characterized in that: The drying condition in the first step is drying at 150-200° C. for 1-2 h.

7. The method for extracting and recovering rare and precious metal iridium from a metal molten salt according to claim 1, characterized in that: The drying condition in the second step is drying at 300°C for 1-2 hours.

8. The method for extracting and recovering rare and precious metal iridium from a metal molten salt according to claim 1, characterized in that: The mass fraction of the hydrochloric acid solution in the first step is 15%.

9. The method for extracting and recovering rare and precious metal iridium from a metal molten salt according to claim 1, characterized in that: The mass fraction of the NaOH solution added in the second step is 30%.

10. The method for extracting and recovering rare and precious metal iridium from metal molten salt according to claim 1, characterized in that: The mass fraction of hydrogen in ultrapure hydrogen is not less than 99.9999%.