Method for separating and recovering precious metals from waste platinum group metal catalysts

Abstract

The application discloses a method for separating and recovering noble metals from waste platinum group metal catalysts, and belongs to the technical field of waste treatment and resource utilization. The method takes full advantage of the characteristics of microwave heat treatment, such as uniform heating, fast heating rate and high heating efficiency, can reach the required temperature in a short time, quickly synthesizes choline chloride / p-toluenesulfonic acid deep eutectic solvent (DES), and uses the deep eutectic solvent to leach the metals in the waste catalyst, and adopts DES hydrophilic phase-quaternary ammonium phosphonium ionic liquid hydrophobic phase liquid-liquid extraction to efficiently and quickly realize the enrichment of platinum and palladium, and through the stripping of palladium by thiourea and hydrochloric acid and the stripping of platinum by nitric acid, platinum and palladium products are selectively obtained. In the method, the high pressure (6000 kPa) and high temperature (250 DEG C) and necessary high temperature (800 DEG C) heat pretreatment steps in the traditional hydrometallurgy waste catalyst recovery process and the consumption of a large amount of acid are avoided.

Description

Technical Field

[0001] This invention belongs to the field of waste treatment and resource utilization technology, specifically relating to a method for separating and recovering precious metals from waste platinum group metal catalysts. Background Technology

[0002] Platinum group metals (PGMs) are indispensable strategic metal resources in the automotive, petrochemical, energy, and defense industries, possessing unique physical and chemical properties such as excellent catalytic activity, high electrical conductivity, and chemical stability. Due to these properties, PGMs occupy a crucial position in many modern industrial and technological applications, encompassing catalysts, electronics, petroleum refining, and medical applications. Among them, platinum, palladium, and rhodium are particularly important in automotive exhaust catalytic treatment and petrochemical fields.

[0003] Currently, PGMs mineral resources are extremely scarce. In 2023, demand for Pt, Pd, and Rh all increased; however, the supply shortage further widened the supply-demand gap. Since 2019, global recycled PGMs production has been declining year by year. Because catalysts are the primary application area for PGMs, spent catalysts have become the most critical secondary resource type for PGMs. Compared to the average PGMs grade of approximately 0.4 g / t in raw ore, spent catalysts contain extremely high PGMs content (100-3000 g / t), thus becoming important strategic materials. However, in my country, the recovery rate of PGMs from spent catalysts is less than 40%, highlighting the urgent need to break through key processing technologies to improve the recycling rate of spent PGMs catalysts.

[0004] Currently, platinum enrichment from spent PGMs catalysts is mainly achieved through pyrometallurgical and hydrometallurgical methods. Pyrometallurgy is a mature metallurgical technology used to extract metals from primary ores and various wastes. After initial physical separation, the waste is mixed with fluxes (SiO2, CaO, etc.), reducing agents, and metal catchers (Cu, Fe, etc.) for smelting. The precious metals (PGMs) are then melted and collected in the enrichment. The PGMs carriers (ceramics, alumina, etc.) are transferred to the slag, with a catcher content of less than 0.2%. The PGMs-containing enrichment is then cast into anodes for further electrorefining, achieving recovery rates as high as 99%. However, pyrometallurgy requires a continuous and substantial input of waste to be profitable, and the capital investment in smelters is high. High energy consumption, significant emissions, and flux consumption are the main environmental problems associated with PGMs recovery using pyrometallurgy. Future research should focus on making its operation more sustainable by reducing energy consumption, waste generation, and flux consumption to minimize environmental impact. Hydrometallurgy is another commonly used method for extracting precious metals (PGMs) from spent PGMs catalysts, offering advantages such as low energy consumption and high efficiency. The most common leaching system combines high concentrations of hydrochloric acid with oxidants such as nitric acid, hydrogen peroxide, or sodium chlorate, as PGM-chloride complexes are highly stable in acidic environments. Hydrometallurgy can be used for direct extraction from spent PGMs or for recovering PGMs from the leachate through solution separation and purification techniques. Compared to pyrometallurgy, hydrometallurgy offers advantages such as lower operating temperatures and higher extraction efficiency, thereby reducing energy consumption and carbon emissions. Furthermore, the capital investment in equipment and infrastructure for hydrometallurgy is significantly lower than that for pyrometallurgy. However, hydrometallurgy also has limitations such as chemical reagent consumption and wastewater discharge, which can be reduced by selecting inexpensive and renewable reagents and applying appropriate wastewater treatment processes. In summary, the total recovery rate of spent PGMs catalysts in my country is low, and both existing pyrometallurgical and hydrometallurgical methods have certain limitations. A green, efficient, and short-process method for PGMs recovery is urgently needed. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a method for separating and recovering precious metals from waste platinum group metal catalysts.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for separating and recovering precious metals from spent platinum group metal catalysts includes the following steps:

[0008] (1) The waste platinum group metal catalyst was crushed, ground, and dissolved in HCl solution to obtain a waste catalyst solution;

[0009] (2) Then, choline chloride and p-toluenesulfonic acid were subjected to microwave reaction to prepare a eutectic solvent;

[0010] (3) Mix the eutectic solvent, nitric acid, waste catalyst solution and water and then carry out microwave reaction, solid-liquid separation, to obtain enriched liquid and slag;

[0011] (4) Dissolve quaternary ammonium phosphate (trihexyl(tetradecyl)phosphine chloride) in toluene to obtain a quaternary ammonium phosphate (trihexyl(tetradecyl)phosphine chloride solution;

[0012] (5) The enrichment solution and the quaternary ammonium phosphate (trihexyl(tetradecyl)phosphine chloride solution were mixed and stirred for extraction. After solid-liquid separation, hydrophilic and hydrophobic phases were obtained.

[0013] (6) Add water to the hydrophobic phase, then add hydrochloric acid and thiourea to separate palladium, then add water and nitric acid to separate platinum. The final liquid is the hydrophobic phase ionic liquid residue.

[0014] (7) Add hydrochloric acid to the hydrophobic ionic liquid residue from step (6) and the hydrophilic phase obtained in step (5) respectively to remove the remaining impurity metals, and wash with water to purify for recycling.

[0015] The hydrophilic phase in step (7) of this invention can be recycled after impurity removal in step (3) to replace the eutectic solvent in step (3) without affecting the leaching rate and recovery rate of platinum and palladium.

[0016] The hydrophobic ionic liquid residue in step (7) of this invention can be recycled after impurity removal in step (5) to replace the quaternary ammonium phosphate (trihexyl(tetradecyl)phosphine chloride solution in step (5)) without affecting the extraction rate and recovery rate of platinum and palladium.

[0017] In a preferred embodiment of the present invention, the concentration of the HCl solution is 1-9 mol / L; the mass-to-volume ratio of the waste platinum group metal catalyst to the HCl solution is 1 g: (3-5) ml.

[0018] In a preferred embodiment of the present invention, the molar ratio of choline chloride to p-toluenesulfonic acid is 1:1.8.

[0019] In a preferred embodiment of the present invention, in step (2), the microwave power is 800W, the temperature is 80℃, the time is 10-30min, and the rotation speed is 300rpm.

[0020] This invention utilizes a microwave method to prepare eutectic solvents, which reduces the generation time and enables rapid synthesis. Conversely, using a conventional water bath, eutectic solvents cannot be generated at the same temperature and time as with microwaves; the time required is more than six times longer.

[0021] In a preferred embodiment of the present invention, the volume ratio of the eutectic solvent, nitric acid and waste catalyst solution is 5:1:1, and the volume ratio of the total volume of the eutectic solvent, nitric acid and waste catalyst solution to the volume of water is 1:1-5.

[0022] In a preferred embodiment of the present invention, in step (3), the microwave power is 800W, the temperature is 80℃, and the time is 90-120min.

[0023] As a preferred embodiment of the present invention, the molar concentration of the quaternary ammonium phosphate (trihexyl(tetradecyl)phosphine chloride) in toluene is 0.005-0.05 mol / L, and more preferably, the molar concentration of the quaternary ammonium phosphate (trihexyl(tetradecyl)phosphine chloride) in toluene is 0.02 mol / L.

[0024] In a preferred embodiment of the present invention, the concentration ratio of the quaternary ammonium phosphate (trihexyl(tetradecyl)phosphine chloride solution and the enrichment solution is 1:1-2.

[0025] In a preferred embodiment of the present invention, in step (6), the volume ratio of the platinum-palladium metal-enriched hydrophobic phase to water is 1:1; the concentrations of hydrochloric acid and thiourea are 0.5 mol / L and 0.1 mol / L, respectively; and the concentration of nitric acid is 1 mol / L.

[0026] Compared with existing technologies, the advantages of this invention are as follows: This invention utilizes DES hydrophilic phase-quaternary ammonium phosphate ionic liquid hydrophobic phase liquid-liquid extraction to achieve efficient and rapid enrichment of platinum and palladium and separation of rhodium. Finally, palladium is stripped by thiourea and hydrochloric acid, and platinum is stripped by nitric acid, selectively yielding platinum and palladium products. This method also avoids the high-pressure (6000 kPa), high-temperature (250°C), and necessary high-temperature (800°C) thermal pretreatment steps required in traditional hydrometallurgical waste catalyst recovery processes, as well as the consumption of large amounts of acid. Furthermore, the eutectic solvent and ionic liquid used in this invention can be recycled, avoiding the discharge of large amounts of waste liquid in traditional hydrometallurgical processes. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a method for separating and recovering precious metals from waste platinum group metal catalysts. Detailed Implementation

[0028] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0029] Example 1

[0030] like Figure 1 As shown, a method for separating and recovering precious metals from spent platinum group metal catalysts includes the following steps:

[0031] (1) The commercially available platinum group metal waste catalyst is crushed, ground to 200 mesh and dissolved in 1 mol / L HCl solution to obtain waste catalyst solution, wherein the solid-liquid ratio of platinum group metal waste catalyst to HCl solution is 1 g: 3 ml.

[0032] (2) Then, choline chloride and p-toluenesulfonic acid in a molar ratio of 1:1.8 were mixed in a 100ml round-bottom flask and placed in a microwave reactor to react under the conditions of 800W, 80℃, 300rpm and 10min to obtain a eutectic solvent (DES).

[0033] (3) DES, nitric acid and waste catalyst solution are mixed in a volume ratio of 5:1:1 to obtain a hydrophilic DES phase, and then water is added to obtain a diluted hydrophilic DES phase. The volume ratio of the hydrophilic DES phase to water is 1:2.

[0034] (4) The diluted hydrophilic DES phase was placed in a microwave reactor and mixed at 80°C, 800W and 120min. The solution was then placed in the microwave reactor for platinum group metal leaching enrichment. The centrifugation speed was 4000rpm and centrifugation was 10min to obtain enriched solution and residue. The leaching rates of platinum and palladium in the enriched solution were 96.45% and 98.94%, respectively.

[0035] (5) Dissolve 0.02 mol / L trihexyl(tetradecyl)phosphine chloride in toluene.

[0036] (6) The enrichment solution and trihexyl(tetradecyl)phosphine chloride solution were mixed and stirred at 300 rpm for 20 min for extraction. After solid-liquid separation by centrifugation at 4000 rpm for 10 min, hydrophilic DES phase and hydrophobic phase were obtained. Platinum and palladium were in the hydrophobic ionic liquid phase, and the extraction rates of platinum and palladium were 94.89% and 95.91%, respectively.

[0037] (7) Add an equal volume of water to the hydrophobic phase, then add 0.5 mol / L hydrochloric acid and 0.1 mol / L thiourea to strip palladium and filtrate. Add an equal volume of water and 1 mol / L nitric acid to the filtrate to strip platinum and ionic liquid. The stripping rates of platinum and palladium are 98.85% and 98.69%, respectively.

[0038] (8) The hydrophilic and hydrophobic residual liquids are purified with water and 5 mol / L HCl and centrifuged before being recycled.

[0039] In Example 1, the recoveries of platinum and palladium were 95.34% and 94.65%, respectively.

[0040] Table 1 Chemical composition of spent PGMs catalysts

[0041]

[0042] (*Unit is g / t)

[0043] Example 2

[0044] like Figure 1 As shown, a method for separating and recovering precious metals from spent platinum group metal catalysts includes the following steps:

[0045] (1) The platinum group metal waste catalyst (chemical composition as shown in Table 1) was crushed, ground to 200 mesh and dissolved in 1 mol / L HCl solution to obtain waste catalyst solution, wherein the solid-liquid ratio of platinum group metal waste catalyst to HCl solution is 1 g: 5 ml.

[0046] (2) Then, choline chloride and p-toluenesulfonic acid in a molar ratio of 1:1.8 were mixed in a 100ml round-bottom flask and placed in a microwave reactor to react under the conditions of 800W, 80℃, 300rpm and 10min to obtain a eutectic solvent (DES).

[0047] (3) DES, nitric acid and waste catalyst solution are mixed in a volume ratio of 5:1:1 to obtain a hydrophilic DES phase, and then water is added to obtain a diluted hydrophilic DES phase. The volume ratio of the hydrophilic DES phase to water is 1:1.

[0048] (4) The diluted hydrophilic DES phase was placed in a microwave reactor and mixed at 80°C, 800W and 120min. The solution was then placed in the microwave reactor for platinum group metal leaching enrichment. The centrifugation speed was 4000rpm and centrifugation was 10min to obtain enriched solution and residue. The leaching rates of platinum and palladium in the enriched solution were 94.64% and 98.92%, respectively.

[0049] (5) Dissolve 0.02 mol / L trihexyl (tetradecyl)phosphine chloride in toluene.

[0050] (6) The enrichment solution and trihexyl(tetradecyl)phosphine chloride solution were mixed and stirred at 300 rpm for 20 min for extraction. After solid-liquid separation by centrifugation at 4000 rpm for 10 min, hydrophilic DES phase and hydrophobic phase were obtained. Platinum and palladium were in the hydrophobic ionic liquid phase, and the extraction rates of platinum and palladium were 98.98% and 99.03%, respectively.

[0051] (7) Add an equal volume of water to the hydrophobic phase, then add 0.5 mol / L hydrochloric acid and 0.1 mol / L thiourea to strip palladium and filtrate. Add an equal volume of water and 1 mol / L nitric acid to the filtrate to strip platinum and liquid. The stripping rates of platinum and palladium are 98.97% and 98.94%, respectively.

[0052] In Example 2, the recoveries of platinum and palladium were 97.96% and 98.34%, respectively.

[0053] Example 3

[0054] like Figure 1 As shown, a method for separating and recovering precious metals from spent platinum group metal catalysts includes the following steps:

[0055] (1) The platinum group metal waste catalyst (chemical composition as shown in Table 1) was crushed, ground to 200 mesh and dissolved in 1 mol / L HCl solution to obtain waste catalyst solution, wherein the solid-liquid ratio of platinum group metal waste catalyst to HCl solution is 1 g: 4 ml.

[0056] (2) Then, choline chloride and p-toluenesulfonic acid in a molar ratio of 1:1.8 were mixed in a 100ml round-bottom flask and placed in a microwave reactor to react under the conditions of 800W, 80℃, 300rpm and 10min to obtain a eutectic solvent (DES).

[0057] (3) DES, nitric acid and waste catalyst solution are mixed in a volume ratio of 5:1:1 to obtain a hydrophilic DES phase, and then water is added to obtain a diluted hydrophilic DES phase. The volume ratio of the hydrophilic DES phase to water is 1:2.

[0058] (4) The diluted hydrophilic DES phase was placed in a microwave reactor and mixed at 80°C, 800W and 120min. The solution was then placed in the microwave reactor for platinum group metal leaching enrichment. The centrifugation speed was 4000rpm and centrifugation was 10min to obtain enriched solution and residue. The leaching rates of platinum and palladium in the enriched solution were 94.45% and 99.31%, respectively.

[0059] (5) Dissolve 0.05 mol / L trihexyl(tetradecyl)phosphine chloride in toluene.

[0060] (6) The enrichment solution and trihexyl(tetradecyl)phosphine chloride solution were mixed and stirred at 300 rpm for 15 min for extraction. After solid-liquid separation by centrifugation at 4000 rpm for 10 min, hydrophilic DES phase and hydrophobic phase were obtained. Platinum and palladium were in the hydrophobic ionic liquid phase, and the extraction rates of platinum and palladium were 91.35% and 82.77%, respectively.

[0061] (7) Add an equal volume of water to the hydrophobic phase, then add 0.5 mol / L hydrochloric acid and 0.1 mol / L thiourea to strip palladium and filtrate. Add an equal volume of water and 1 mol / L nitric acid to the filtrate to strip platinum and liquid. The stripping rates of platinum and palladium are 99.25% and 98.72%, respectively.

[0062] In Example 3, the recoveries of platinum and palladium were 93.74% and 98.03%, respectively.

[0063] Example 4

[0064] The method for separating and recovering precious metals from waste platinum group metal catalysts described in this embodiment differs from that in Example 1 in that the DES in step (3) is replaced with the hydrophilic DES phase obtained in step (6) of Example 1, which has been used once.

[0065] Replace the trihexyl (tetradecyl)phosphine chloride solution used once in step (6) with the ionic liquid obtained in step (7) of Example 1;

[0066] In step (4), the leaching rates of platinum and palladium in the enrichment solution were 94.45% and 98.31%, respectively.

[0067] In step (6), the platinum-palladium extraction rates were 91.37% and 94.68%, respectively.

[0068] In step (7), the stripping rates of platinum and palladium were 99.27% ​​and 99.33%, respectively.

[0069] In Example 2, the recoveries of platinum and palladium were 84.69% and 92.64%, respectively.

[0070] Example 5

[0071] The method for separating and recovering precious metals from waste platinum group metal catalysts described in this embodiment differs from that in Example 1 in that the DES in step (3) is replaced with the hydrophilic DES phase obtained in step (6) of Example 1, which is reused four times.

[0072] Replace the trihexyl (tetradecyl)phosphine chloride solution in step (6) with the liquid obtained in step (7) of Example 1, which was reused 4 times;

[0073] In step (4), the leaching rates of platinum and palladium in the enrichment solution were 93.88% and 96.79%, respectively.

[0074] In step (6), the platinum-palladium extraction rates were 94.65% and 93.98%, respectively.

[0075] In step (7), the stripping rates of platinum and palladium were 98.91% and 99.14%, respectively.

[0076] In Example 2, the recoveries of platinum and palladium were 87.88% and 90.18%, respectively.

[0077] A comparison of Examples 4 and 5 with Examples 1-3 shows that the recycled hydrophilic DES phase-trihexyl(tetradecyl)phosphine chloride solution has little impact on the liquid-liquid extraction rate, leaching rate, stripping rate, and recovery rate of platinum and palladium.

[0078] Comparative Example 1

[0079] The only difference between this comparative example and Example 1 is that the concentration of the HCl solution in step (1) is different; the concentration of the HCl solution is 0.1 mol / L.

[0080] In step (4), the leaching rates of platinum and palladium in the enrichment solution were 30.53% and 38.69%, respectively.

[0081] In step (6), the platinum-palladium extraction rates were 96.78% and 98.44%, respectively.

[0082] In step (7), the stripping rates of platinum and palladium were 98.63% and 98.47%, respectively.

[0083] In Comparative Example 1, the recoveries of platinum and palladium were 28.17% and 37.50%, respectively.

[0084] Comparative Example 2

[0085] The only difference between this comparative example and Example 1 is that the concentration of the HCl solution in step (1) is different; the concentration of the HCl solution is 2 mol / L.

[0086] In step (4), the leaching rates of platinum and palladium in the enrichment solution were 95.73% and 98.29%, respectively.

[0087] In step (6), the platinum and palladium extraction rates were 90.28% and 92.65%, respectively.

[0088] In step (7), the stripping rates of platinum and palladium were 98.79% and 98.66%, respectively.

[0089] In Comparative Example 2, the recoveries of platinum and palladium were 85.37% and 88.30%, respectively.

[0090] A comparison of Comparative Examples 1 and 2 with Example 1 shows that HCl concentration has a certain impact on both platinum-palladium microwave leaching and extraction. Too low a HCl concentration significantly reduces the platinum-palladium leaching rate, leading to a substantial decrease in platinum-palladium recovery. Too high a HCl concentration reduces the platinum-palladium extraction rate, resulting in a decrease in platinum-palladium recovery.

[0091] Comparative Example 3

[0092] The only difference between this comparative example and Example 1 is that the leaching reactor in step (4) is different. In this comparative example, the leaching reactor is a muffle furnace, and the leaching and enrichment of platinum group metals is carried out at 80°C for 120 min. The centrifugation speed is 4000 rpm and the centrifugation time is 10 min.

[0093] In step (4), the leaching rates of platinum and palladium in the enrichment solution were 60.75% and 64.31%, respectively.

[0094] In step (6), the platinum-palladium extraction rates were 95.27% and 95.88%, respectively.

[0095] In step (7), the stripping rates of platinum and palladium were 99.34% and 99.17%, respectively.

[0096] In Comparative Example 3, the recoveries of platinum and palladium were 57.49% and 61.14%, respectively.

[0097] By comparing Example 1 and Comparative Example 3, it can be seen that, compared with conventional reactors, the microwave reactor, through microwave-enhanced leaching process, greatly improves the leaching rate of platinum and palladium under the same reaction time and temperature conditions, and also significantly improves the recovery rate.

[0098] Comparative Example 4

[0099] The only difference between this comparative example and Example 1 is that the eutectic solvent in steps (2) and (3) is different. In this comparative example, the eutectic solvent is obtained by mixing trioctylphosphine oxide and 1-butyric acid in a 1:1 ratio in a 100ml round-bottom flask and reacting them in a microwave reactor at 800W, 80℃, 300rpm and 10min.

[0100] In step (4), the leaching rates of platinum and palladium in the enrichment solution were 86.19% and 85.56%, respectively.

[0101] In step (6), the platinum-palladium extraction rates were 92.85% and 95.02%, respectively.

[0102] In step (7), the stripping rates of platinum and palladium were 99.27% ​​and 99.35%, respectively.

[0103] In Comparative Example 4, the recoveries of platinum and palladium were 79.44% and 80.77%, respectively.

[0104] Comparative Example 5

[0105] The only difference between this comparative example, a method for separating and recovering precious metals from waste platinum group metal catalysts, and Example 1 is that the trihexyl (tetradecyl)phosphine chloride in step (5) is replaced with trihexyl (tetradecyl)phosphonium bromide of equal concentration.

[0106] In step (4), the leaching rates of platinum and palladium in the enrichment solution were 94.31% and 97.94%, respectively.

[0107] In step (6), the platinum-palladium extraction rates were 81.23% and 84.09%, respectively.

[0108] In step (7), the stripping rates of platinum and palladium were 99.09% and 99.14%, respectively.

[0109] In Comparative Example 5, the recoveries of platinum and palladium were 75.91% and 81.64%, respectively.

[0110] By comparing Example 1 and Comparative Examples 4 and 5, it can be seen that the highest platinum and palladium recovery rate can be obtained by synergistic leaching, extraction and stripping of platinum and palladium with choline chloride-p-toluenesulfonic acid and trihexyl(tetradecyl)phosphonium chloride.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, 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 essence and scope of the technical solutions of the present invention.

Claims

1. A method for separating and recovering precious metals from spent platinum group metal catalysts, characterized in that: Includes the following steps: (1) The waste platinum group metal catalyst was crushed, ground and dissolved in HCl solution to obtain the waste catalyst solution; (2) Then, choline chloride and p-toluenesulfonic acid are reacted by microwave to prepare a eutectic solvent; (3) Mix the eutectic solvent, nitric acid, waste catalyst solution and water and then carry out microwave reaction, solid-liquid separation, to obtain enriched liquid and slag; (4) Dissolve trihexyl(tetradecyl)phosphine chloride in toluene to obtain a trihexyl(tetradecyl)phosphine chloride solution; (5) The enrichment solution and trihexyl(tetradecyl)phosphine chloride solution were mixed and stirred for extraction. After solid-liquid separation, hydrophilic and hydrophobic phases were obtained. (6) Add water to the hydrophobic phase, then add hydrochloric acid and thiourea to separate palladium, then add water and nitric acid to separate platinum. The final liquid is the hydrophobic ionic liquid residue. (7) Add hydrochloric acid to the hydrophobic ionic liquid residue from step (6) and the hydrophilic phase obtained in step (5) respectively to remove the remaining impurity metals, and wash with water to purify for recycling. In step (3), the microwave power is 800W, the temperature is 80℃, and the time is 90-120min.

2. The method for separating and recovering precious metals from spent platinum group metal catalysts according to claim 1, characterized in that: The concentration of the HCl solution is 1-9 mol / L; the solid-liquid ratio of the waste platinum group metal catalyst to the HCl solution is 1 g:(3-5) ml.

3. The method for separating and recovering precious metals from spent platinum group metal catalysts according to claim 1, characterized in that, The molar ratio of choline chloride to p-toluenesulfonic acid is 1:1.5-2.

4. The method for separating and recovering precious metals from spent platinum group metal catalysts according to claim 1, characterized in that, In step (2), the microwave power is 800W, the temperature is 80℃, the time is 10-30min, and the rotation speed is 300rpm.

5. The method for separating and recovering precious metals from spent platinum group metal catalysts according to claim 1, characterized in that, The volume ratio of the eutectic solvent, nitric acid, and waste catalyst solution is 5:1:1, and the total volume of the eutectic solvent, nitric acid, and waste catalyst solution to water is 1:1-5.

6. The method for separating and recovering precious metals from spent platinum group metal catalysts according to claim 1, characterized in that, The molar concentration of the trihexyl(tetradecyl)phosphine chloride dissolved in toluene is 0.005-0.05 mol / L.

7. The method for separating and recovering precious metals from spent platinum group metal catalysts according to claim 1, characterized in that, The volume ratio of the trihexyl (tetradecyl)phosphine chloride solution to the enrichment solution is 1:1-2.

8. The method for separating and recovering precious metals from spent platinum group metal catalysts according to claim 1, characterized in that, In step (6), the volume ratio of the platinum-palladium metal-enriched hydrophobic phase to water is 1:1; the concentrations of hydrochloric acid and thiourea are 0.5 mol / L and 0.1 mol / L, respectively; and the concentration of nitric acid is 1 mol / L.

9. The method for separating and recovering precious metals from spent platinum group metal catalysts according to claim 1, characterized in that, In step (7), the concentration of HCl is 3-5 mol / L.

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