Method for recovering three-way catalyst by wet process

Abstract

The invention discloses a method for recovering a three-way catalyst by a wet process, and belongs to the technical field of noble metal catalyst recovery. The method comprises the following steps: carrying out crushing, roasting and alkaline hydrolysis on the three-way catalyst, reducing to obtain reducing slag, dissolving and precipitating to obtain palladium and platinum, and carrying out high-temperature quenching and acidolysis precipitation on rhodium-containing insoluble slag remained after dissolving to obtain rhodium; wherein special precipitants are adopted during precipitation of platinum, palladium and rhodium. According to the method, rhodium, platinum and palladium are recycled in a step-by-step leaching and step-by-step recycling mode, and the leaching rate and the recycling rate of the three kinds of metal are increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of precious metal catalyst recovery, and particularly relates to a method for wet recycling of three-way catalysts. Background Art

[0002] The three-way catalytic converter is the most important off-board purification device installed in the exhaust of automobiles. It can convert harmful gases such as CO, HC, and NOx discharged from automobile exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction reactions. When the high-temperature automobile exhaust passes through the three-way catalytic converter, the purification agent therein enhances the activity of the three gases of CO, HC, and NOx, prompting them to undergo certain oxidation-reduction chemical reactions. Among them, CO is oxidized into colorless and non-toxic carbon dioxide gas at high temperature; HC compounds are oxidized into water (H2O) and carbon dioxide at high temperature; NOx is reduced into nitrogen and oxygen. The three harmful gases become harmless gases, purifying the automobile exhaust. The carrier component of the three-way catalytic converter is a porous ceramic material, covered with a layer of precious metals such as platinum, rhodium, palladium and rare earth coatings for purifying exhaust gas. The three-way catalytic converter is similar to a muffler. Its outer part is made of a double-layer stainless steel thin plate in a cylindrical shape, and heat-insulating material - asbestos fiber felt is installed in the double-layer thin plate sandwich; inside, the purification agent is installed in the middle of the net-shaped partition. The purification agent consists of a carrier and a catalyst; the carrier is generally made of aluminum oxide, and its shapes include spherical, polyhedral and net-shaped partitions, etc.; the purification agent actually plays a catalytic role and is also called a catalyst. The catalyst used is platinum, rhodium, and palladium metal, which is sprayed on the carrier to form the purification agent.

[0003] Each three-way catalytic converter uses 1-2 g of platinum group metals, and the three-way catalytic converter will fail and be replaced after being used for about 100,000 kilometers. Currently, the three-way catalytic converters replaced annually plus those from scrapped vehicles are about 1,000 tons, containing about 20 t of platinum, palladium, and rhodium, with a value of over 10 billion yuan. Therefore, it is necessary to recycle platinum, palladium, and rhodium precious metals to improve their economic value and resource recycling utilization rate, reduce the dependence on newly mined resources, and reduce exhaust gas pollution.

[0004] Methods for recovering platinum group metals from three-way catalysts can generally be classified into the following treatment processes: (1) Carrier complete dissolution method: This method is used to treat granular and columnar catalysts composed of early γ-alumina. First, the catalyst is ground to 200 mesh, and then the carrier is dissolved with sulfuric acid. The insoluble residue is leached with hydrochloric acid and chlorine to recover platinum group metals. The platinum group metals in the leachate are precipitated and recovered with sulfur dioxide. The recovery rates of this method are 88-94% for platinum, 88-96% for palladium, and 84-88% for rhodium. (2) Carrier insoluble method: This method is used to recover platinum group metals from catalysts with cordierite as the carrier. It only dissolves the alumina coating containing the catalyst, and the cordierite carrier is basically not eroded. First, the catalyst is broken into pieces of one inch, and the γ-Al2O3 on the surface of the carrier is dissolved with dilute sulfuric acid, and then washed by decantation. Three-stage decantation washing can quantitatively recover the dissolved platinum group metals, and then sulfur dioxide is used as the reducing precipitant and Te is used as the trapping agent. The recovery rates of this method are 85-92% for platinum, 85-93% for palladium, and 78-85% for rhodium. (3) Plasma enrichment method: The high temperature generated by the plasma can reach above 2000 °C. Without adding a flux, alumina and cordierite are directly melted, and platinum group metals enter the high-silicon ferroalloy slag. After the ferroalloy is spray granulated, impurities are dissolved with sulfuric acid and air to produce a leach residue containing platinum group metals. Platinum group metals are then recovered from this residue. This method has problems of lead pollution, high power consumption, and difficult alloy dissolution, resulting in low metal recovery rates and high costs. (4) Copper smelting collaborative recovery method: During the process of pyrometallurgical copper smelting, the catalyst is added, so that PGMS enter the matte and blister copper. During the electrolysis of blister copper, PGMS enter the copper anode slime, and then PGMS are recovered from the copper anode slime. Therefore, the recovery rate of copper during the smelting process determines the yield of PGMS. Generally, the recovery rates of platinum, palladium, and rhodium are relatively high, above 90%, but the production cycle is long, and it must be processed in cooperation with copper smelting enterprises. Summary of the Invention

[0005] In view of the above technical problems, the present invention provides a method for wet recovering three-way catalysts, which adopts the method of stepwise leaching and stepwise recovery to recover rhodium, platinum, and palladium respectively, improving the leaching rate and recovery rate of the three metals.

[0006] To achieve the above object, the present invention provides a method for wet recovering three-way catalysts, including the following steps: (1) Crushing the three-way catalytic converter, roasting at 600-800 °C for 3-5 h, and ball milling to obtain materials; (2) Removing impurities by alkaline hydrolysis, and retaining the reduction residue after reduction treatment; (3) Dissolving the reduction residue in aqua regia, and separating to obtain a rhodium-containing insoluble residue and a solution; (4) Adding a palladium precipitant and a platinum precipitant to the solution in sequence to obtain elemental palladium and elemental platinum; (5) The rhodium-containing insoluble slag is mixed with base metals and then quenched at high temperature, and the base metals are removed by acid leaching to obtain rhodium-containing slag; (6) The rhodium-containing slag is dissolved in aqua regia and then a rhodium precipitant is added to obtain rhodium precipitate; (7) The rhodium precipitate is mixed with a reducing agent and reduced to obtain elemental rhodium.

[0007] Preferably, the particle size of the material described in step (1) is 80-120 mesh.

[0008] Preferably, the base metal removal by alkaline hydrolysis in step (2) is to mix the material with an alkaline solution, stir at 90-100 rpm / min, heat up to 80-95 °C, and then hydrolyze for 0.5-2 h.

[0009] Further preferably, the alkaline solution is a sodium hydroxide solution with a mass concentration of 8-15%, and the mass ratio of the material to the alkaline solution is 1:5-6.

[0010] Preferably, the reduction treatment described in step (2) is to add a reducing agent to the solution after impurity removal and boil for 0.3-1 h.

[0011] Further preferably, the reducing agent is hydrazine hydrate; the dosage of the reducing agent is 25-35% of the total mass of all metals in the solution.

[0012] Preferably, the mass ratio of the reduced slag to aqua regia in step (3) is 1:7-9.

[0013] Preferably, the palladium precipitant described in step (4) is dimethylglyoxime; the platinum precipitant is ammonium chloride; the dosage of the palladium precipitant is a molar ratio of 1.1-1.3:1 to palladium in the solution, and the dosage of the platinum precipitant is a molar ratio of 1.1-1.3:1 to platinum in the solution.

[0014] Preferably, the mass ratio of the rhodium-containing insoluble slag to base metals in step (5) is 1:3.5-4, and the high-temperature quenching condition is quenching at 800-850 °C for 5-8 h; the acid used for removing base metals by acid leaching is a 5-8 M hydrochloric acid solution.

[0015] Further preferably, the base metal is any one of zinc powder, aluminum powder, magnesium powder, and aluminum-zinc mixed powder.

[0016] Even more preferably, the particle size of the zinc powder, aluminum powder, magnesium powder, and aluminum-zinc mixed powder is 200-300 mesh.

[0017] Preferably, the mass ratio of the rhodium-containing slag to aqua regia in step (6) is 1:7-9.

[0018] Preferably, the rhodium precipitant described in step (6) is diethylenetriamine; the molar ratio of the rhodium precipitant to rhodium in the solution is 1.1-1.3:1.

[0019] Preferably, the reducing agent in step (7) is hydrazine hydrate; the molar ratio of the reducing agent to rhodium in the rhodium precipitate is 1.1-1.3:1.

[0020] The beneficial effects of the present invention are as follows: By adopting the method of step-by-step leaching and step-by-step recovery to separately recover rhodium, platinum and palladium, the leaching rates (the laboratory leaching rate is about 100%) and recovery rates of the three metals are improved, so that the recovery rates of palladium and platinum in the three-way catalytic converter reach more than 98%, the recovery rate of rhodium reaches more than 95%, and the product purity reaches 99.95%, which improves its economic value and facilitates subsequent use.

[0021] Using dimethylglyoxime to precipitate palladium, in an acidic solution, palladium ions can form a chelate precipitate with dimethylglyoxime; this reaction is based on the fact that palladium belongs to a weak alkaline medium, and dimethylglyoxime, as an organic precipitant, can react with palladium to form a bright yellow precipitate. Therefore, only palladium can be quantitatively precipitated without affecting other metal ions, and it has good selectivity.

[0022] Using diethylenetriamine as a precipitant for rhodium, under specific conditions, it forms a water-insoluble complex with rhodium, efficiently separating rhodium from other metals, and has the advantages of low cost, environmental friendliness, simple operation, easy control, etc.

[0023] The method adopted by the present invention has low equipment investment cost and production cost, short process, and high yield, and can be widely used in the recovery of platinum, palladium and rhodium metals in automotive exhaust three-way catalytic converters. Description of the Drawings

[0024] Figure 1 It is the process flow chart of the present invention. Detailed Embodiments

[0025] The technical solutions of the present invention will be further explained and illustrated below in conjunction with the drawings and specific embodiments. It should be noted that the following embodiments are only the preferred embodiments of the present invention and should not be construed as limitations on the present invention. The protection scope of the present invention should be determined by the content recorded in the claims. Modifications and substitutions made by those skilled in the art to the technical solutions of the present invention without creative efforts all fall within the protection scope of the present invention.

[0026] Example 1 (1) Take the automotive exhaust three-way catalytic converter, cut and crush it, calcine it at 700 °C for 4 h to remove organic substances and carbon, and then ball mill it to 100 mesh to obtain the material; (2) Mix the material with a 10% sodium hydroxide solution in a mass ratio of 1:5.5, stir and heat it to 90 °C at 90 rpm / min, and continue to stir for 1 h to complete impurity removal; (3) While stirring, add 100 mL of hydrazine hydrate solution (mass fraction 50%) such that the mass of hydrazine hydrate is 30% of the total metal mass in the solution. Heat to boiling, boil for 0.5 h, then cool to 40 °C and perform solid-liquid separation to retain the reduced residue. (4) Mix the reduced residue and aqua regia in a mass ratio of 1:8. After stirring and dissolving, add potassium nitrate solution to drive off nitrates. After the nitrate expulsion is complete, perform solid-liquid separation to obtain a palladium-platinum solution and a rhodium-containing insoluble residue. (5) Directly add dimethylglyoxime (where the molar ratio of palladium to dimethylglyoxime is 1:1.2) to the palladium-platinum solution as a precipitant. Stir and mix evenly for precipitation. After no new precipitation appears, perform solid-liquid separation to obtain palladium precipitate and a platinum solution. (6) Directly add ammonium chloride (where the molar ratio of platinum to ammonium chloride is 1:1.2) to the platinum solution as a precipitant. Stir and mix evenly, then perform precipitation. After no new precipitation appears, perform solid-liquid separation to obtain a platinum precipitate. (7) Complex the palladium precipitate with ammonia water to adjust the pH of the solution to 7.5 (complexing temperature is 65 °C). After dissolution, perform solid-liquid separation, then slowly add hydrochloric acid solution to the filtrate to adjust the pH of the solution to 1.5 for acidification precipitation. After no new precipitation occurs, perform solid-liquid separation to obtain a palladium precipitate; repeat three times to obtain purified spongy palladium. (8) Mix the platinum precipitate with aqua regia, dissolve, and then perform solid-liquid separation. Add ammonium chloride to the filtrate as a precipitant. Stir and mix evenly, then perform precipitation. After no new precipitation appears, perform solid-liquid separation to obtain a platinum precipitate; repeat three times to obtain purified spongy platinum; where the molar ratio of platinum in the filtrate to ammonium chloride is 1:1.2. (9) Mix the rhodium-containing insoluble residue and zinc powder in a mass ratio of 1:4, then perform high-temperature quenching at 820 °C for 6 h. Then mix the quenched product with 6 M hydrochloric acid solution to dissolve, remove the excess zinc powder, and perform solid-liquid separation to obtain a rhodium-containing residue. (10) Mix the rhodium-containing residue and aqua regia in a mass ratio of 1:8. After stirring and dissolving, perform solid-liquid separation to obtain a rhodium-containing solution. Add diethylenetriamine to the rhodium-containing solution as a precipitant. Stir and react until no new precipitation appears, then perform solid-liquid separation. Re-mix the solid product with aqua regia to dissolve, and add again for precipitation. Repeat 3 times to obtain a purified rhodium-containing solution. Then add a reducing agent - hydrazine hydrate solution (mass fraction 50%) to the purified rhodium-containing solution. After stirring and reacting, perform solid-liquid separation to obtain elemental rhodium. The mass ratio of rhodium to diethylenetriamine in the rhodium-containing solution is 2:1, and the mass ratio of rhodium to hydrazine hydrate in the purified rhodium-containing solution is 1:2.

[0027] The recovery rate of platinum is 99%, and the purity is 99.95%; the recovery rate of palladium is 98.5%, and the purity is 99.95%; the recovery rate of rhodium is 95%, and the purity is 99.95%.

[0028] Example 2 (1) Take the sheared and crushed three-way catalytic machine of automobile exhaust, calcine it at 600 °C for 5 h, and then ball mill it to 80 mesh as the material; (2) Mix the material with an 8% sodium hydroxide solution in a mass ratio of 1:5, then stir and heat it to 80 °C at 100 rpm / min. Continue stirring for 1 h and then add 50 mL of hydrazine hydrate solution (mass fraction 50%) while stirring, so that the mass of hydrazine hydrate is 25% of the total mass of all metals in the solution. Heat it to boiling, boil for 1 h and then cool it to 40 °C, and perform solid-liquid separation to retain the reduced slag; (3) Mix the reduced slag with aqua regia in a mass ratio of 1:7, stir and dissolve it, and then perform solid-liquid separation to obtain a palladium-platinum solution and a rhodium-containing insoluble slag; (4) Add dimethylglyoxime (where the molar ratio of palladium to dimethylglyoxime is 1:1.1) to the palladium-platinum solution as a precipitant, stir and mix evenly, then perform precipitation. After half an hour, when no new precipitate is generated, perform solid-liquid separation again to obtain palladium precipitate and a platinum solution; (5) Add ammonium chloride (where the molar ratio of platinum to ammonium chloride is 1:1.1) to the platinum solution as a reducing agent, stir and mix evenly, then perform precipitation. After half an hour, when no new precipitate is generated, perform solid-liquid separation again to obtain platinum precipitate; (6) Mix the palladium precipitate with ammonia water to make the pH value of the solution 7 (complexing temperature is 70 °C), dissolve it and then perform solid-liquid separation. Then slowly add hydrochloric acid solution to the filtrate to adjust the pH value of the solution to 1.5 for acidification precipitation. After no new precipitate is generated, perform solid-liquid separation to obtain palladium precipitate; Repeat three times to obtain purified spongy palladium; (7) Mix the platinum precipitate with aqua regia, dissolve it and then perform solid-liquid separation. Add ammonium chloride to the filtrate as a precipitant, stir and mix evenly, then perform precipitation. When no new precipitate appears, perform solid-liquid separation to obtain platinum precipitate; Repeat three times to obtain purified spongy platinum; where the molar ratio of platinum to ammonium chloride in the filtrate is 1:1.2; (8) Mix the rhodium-containing insoluble slag with zinc powder in a mass ratio of 1:3, then perform high-temperature quenching at 800 °C for 8 h. Then mix the quenched product with 6M hydrochloric acid solution to dissolve it, remove the excess zinc powder, and perform solid-liquid separation to obtain rhodium-containing slag; (9) Mix the rhodium-containing slag with aqua regia in a mass ratio of 1:7, stir and dissolve it, and then perform solid-liquid separation to obtain a rhodium-containing solution. Add diethylenetriamine to the rhodium-containing solution as a precipitant, stir and react until no new precipitate appears, then perform solid-liquid separation. Mix the solid product with aqua regia again to dissolve it, and add it again for precipitation. Repeat 3 times to obtain purified rhodium-containing solution. Then add hydrazine hydrate solution (mass fraction 50%) to the purified rhodium-containing solution as a reducing agent, stir and react, and then perform solid-liquid separation to obtain elemental rhodium. Where the mass ratio of rhodium to diethylenetriamine in the rhodium-containing solution is 2:1, and the mass ratio of rhodium to hydrazine hydrate in the purified rhodium-containing solution is 1:2.

[0029] The recovery rate of platinum is 98% and the purity is 99.93%; the recovery rate of palladium is 98% and the purity is 99.92%; the recovery rate of rhodium is 92% and the purity is 99.9%.

[0030] Example 3 (1) Take the sheared and crushed automotive exhaust three-way catalytic machine, calcine it at 800 °C for 3 h, and then ball mill it to 80 mesh as the material. (2) Mix the material with a 15% sodium hydroxide solution in a mass ratio of 1:6, then stir and heat it to 95 °C at 100 rpm / min, continue to stir for 1 h, and then add 200 mL of hydrazine hydrate solution (mass fraction 50%) while stirring, so that the mass of hydrazine hydrate is 35% of the metal amount, heat it to boiling, boil for 0.3 h, and then cool it to 40 °C, and perform solid-liquid separation to retain the reduced slag. (3) Mix the reduced slag with aqua regia in a mass ratio of 1:9, stir and dissolve it, and then perform solid-liquid separation to obtain a palladium-platinum solution and a rhodium-containing insoluble slag. (4) Add dimethylglyoxime (where the molar ratio of palladium to dimethylglyoxime is 1:1.3) to the palladium-platinum solution as a precipitant, stir and mix evenly, then perform precipitation. When no new precipitate is produced after half an hour, perform solid-liquid separation again to obtain palladium precipitate and a platinum solution. (5) Add ammonium chloride (where the molar ratio of platinum to ammonium chloride is 1:1.3) to the platinum solution as a reducing agent, stir and mix evenly, then perform precipitation. When no new precipitate is produced after half an hour, perform solid-liquid separation again to obtain platinum precipitate. (6) Complex the palladium precipitate with ammonia water to make the pH value of the solution 8 (the complexation temperature is 65 °C), dissolve it and then perform solid-liquid separation, and then slowly add hydrochloric acid solution to the filtrate to adjust the pH value of the solution to 1 for acidification precipitation. When no new precipitate is produced, perform solid-liquid separation to obtain palladium precipitate; repeat three times to obtain purified sponge palladium. (7) Mix the platinum precipitate with aqua regia, dissolve it and then perform solid-liquid separation. Add ammonium chloride to the filtrate as a precipitant, stir and mix evenly, then perform precipitation. When no new precipitate appears, perform solid-liquid separation to obtain platinum precipitate; repeat three times to obtain purified sponge platinum; where the molar ratio of platinum in the filtrate to ammonium chloride is 1:1.2. (8) Mix the rhodium-containing insoluble slag with aluminum powder in a mass ratio of 1:3, then anneal it at 850 °C for 5 h, and then mix the annealed product with 8M hydrochloric acid solution to dissolve it, remove the excess zinc powder, and perform solid-liquid separation to obtain a rhodium-containing slag. (9) Mix the rhodium-containing slag with aqua regia at a mass ratio of 1:9, stir and dissolve, then separate the solid from the liquid to obtain a rhodium-containing solution. Add diethylenetriamine as a precipitant to the rhodium-containing solution, stir and react until no new precipitate appears, then separate the solid from the liquid. Re-mix the solid product with aqua regia to dissolve it, and add again for precipitation. Repeat this process 3 times to obtain a purified rhodium-containing solution. Then, add a hydrazine hydrate solution (mass fraction 50%) as a reducing agent to the purified rhodium-containing solution, stir and react, and then separate the solid from the liquid to obtain elemental rhodium. The mass ratio of rhodium to diethylenetriamine in the rhodium-containing solution is 2:1, and the mass ratio of rhodium to hydrazine hydrate in the purified rhodium-containing solution is 1:2.

[0031] The recovery rate of platinum is 98.5% and the purity is 99.95%; the recovery rate of palladium is 98.3% and the purity is 99.95%; the recovery rate of rhodium is 94% and the purity is 99.95%.

[0032] Comparative Example 1 The method and steps are the same as those in Example 1, only omitting step (3). After completing the impurity removal, directly heat up to the boiling point of the solution and boil for 0.5 h, then cool to 40 °C and separate the solid from the liquid to obtain a solid residue, and then obtain elemental platinum, elemental palladium, and elemental rhodium through subsequent treatment. The recovery rate of platinum is 98.5% and the purity is 99.95%; the recovery rate of palladium is 60% and the purity is 99.95%; the recovery rate of rhodium is 93% and the purity is 99.95%.

[0033] From the results, it can be seen that omitting the initial reduction using the hydrazine hydrate solution in step (3) seriously affects the recovery rate of palladium, reducing the recovery rate of palladium from 98.5% to 60%, resulting in serious resource waste.

[0034] Comparative Example 2 The method and steps are the same as those in Example 1, only changing the dosage of hydrazine hydrate in step (3) to 250 mL. Recover elemental platinum, elemental palladium, and elemental rhodium. The recovery rate of platinum is 98.6% and the purity is 99.95%; the recovery rate of palladium is 80% and the purity is 99.95%; the recovery rate of rhodium is 93.2% and the purity is 99.95%.

[0035] Compared with Example 1, increasing the dosage of hydrazine hydrate has no effect on the purity of the product, but the recovery rates of platinum, palladium, and rhodium all decrease. Among them, the recovery rate of palladium decreases the most, by 18.5%, which is due to the difficulty of dissolving palladium oxide.

[0036] Comparative Example 3 The method and steps are the same as those in Example 1, only replacing hydrazine hydrate in step (3) with formic acid. Recover elemental platinum, elemental palladium, and elemental rhodium. The recovery rate of platinum is 98.8% and the purity is 99.95%; the recovery rate of palladium is 97.5% and the purity is 99.95%; the recovery rate of rhodium is 90% and the purity is 99.95%.

[0037] Comparative Example 4 The method and steps are the same as those in Example 1, except that the mass ratio of the reduction slag to aqua regia in step (4) is changed to 1:5. Elemental platinum, elemental palladium and elemental rhodium are recovered. The recovery rate of platinum is 93% and the purity is 99.93%; the recovery rate of palladium is 90% and the purity is 99.90%; the recovery rate of rhodium is 89% and the purity is 99.89%.

[0038] It can be seen from the results that, compared with Example 1, reducing the amount of aqua regia in step (4) has a relatively low impact on the recovery purity of platinum, palladium and rhodium, but the recovery rate decreases significantly. Thus, it can be seen that the minimum mass ratio of the reduction slag to aqua regia should be 1:7, otherwise the recovery rates of platinum, palladium and rhodium will be affected.

[0039] Comparative Example 5 The method and steps are the same as those in Example 1, except that the mass ratio of the reduction slag to aqua regia in step (4) is changed to 1:10. Elemental platinum, elemental palladium and elemental rhodium are recovered. The recovery rate of platinum is 99% and the purity is 99.95%; the recovery rate of palladium is 98.5% and the purity is 99.95%; the recovery rate of rhodium is 95% and the purity is 99.95%.

[0040] It can be seen from the results that, compared with Example 1, increasing the amount of aqua regia in step (4) does not result in significant changes in the recovery rates and purities of platinum, palladium and rhodium. Thus, it can be seen that further increasing the amount of aqua regia will not further improve the recovery of platinum, palladium and rhodium. Considering cost, controlling the mass ratio of the reduction slag to aqua regia between 1:7 - 9 can achieve high-purity and high-recovery rate recovery of platinum, palladium and rhodium, and also control the economic cost.

Claims

1. A method for wet recycling of ternary catalysts, characterized in that: It includes the following steps: (1) Crush the three-way catalytic converter, calcine it at 600 - 800 °C, and ball mill it to obtain a material; (2) Remove impurities by alkaline hydrolysis, and retain the reduction residue after reduction treatment; (3) Dissolve the reduction residue in aqua regia, and separate to obtain a rhodium-containing insoluble residue and a solution; (4) Add a palladium precipitant and a platinum precipitant to the solution in sequence to obtain elemental palladium and elemental platinum; (5) Mix the rhodium-containing insoluble residue with base metals, and perform high-temperature quenching, then remove the base metals by acidolysis to obtain a rhodium-containing residue; (6) Dissolve the rhodium-containing residue in aqua regia and add a rhodium precipitant to obtain a rhodium precipitate; (7) Mix the rhodium precipitate with a reducing agent and reduce it to obtain elemental rhodium.

2. The method for wet recycling of ternary catalyst according to claim 1, characterized in that: The particle size of the material described in step (1) is 80 - 120 mesh.

3. The method for wet recovery of ternary catalyst according to claim 1, characterized in that: The alkaline hydrolysis for impurity removal described in step (2) is to mix the material with an alkaline solution, stir and heat it to 80 - 95 °C, and then perform hydrolysis for 0.5 - 2 h.

4. The method for wet recycling of ternary catalyst according to claim 3, characterized in that: The alkaline solution is a sodium hydroxide solution with a mass concentration of 8 - 15%, and the mass ratio of the material to the alkaline solution is 1:5 - 6.

5. A method for wet recycling of ternary catalysts according to claim 1, characterized in that: The reduction treatment described in step (2) is to add a reducing agent to the solution after impurity removal and boil it for 0.3 - 1 h.

6. The method for wet recovery of a ternary catalyst according to claim 5, wherein: The reducing agent is hydrazine hydrate; the dosage of the reducing agent is 25 - 35% of the total metal mass in the solution.

7. A method for wet recycling of ternary catalysts according to claim 1, characterized in that: The palladium precipitant described in step (4) is dimethylglyoxime; the platinum precipitant is ammonium chloride.

8. A method for wet recycling of ternary catalyst according to claim 1, characterized in that: The mass ratio of the rhodium-containing insoluble residue to the base metal described in step (5) is 1:3.5 - 4, and the high-temperature quenching condition is quenching at 800 - 850 °C for 5 - 8 h; the base metal is any one of zinc powder, aluminum powder, magnesium powder, and aluminum-zinc mixed powder.

9. The method for wet recycling of ternary catalyst according to claim 1, characterized in that: The rhodium precipitant described in step (6) is diethylenetriamine.

10. A method for wet recycling of ternary catalysts according to claim 1, characterized in that: The reducing agent described in step (7) is hydrazine hydrate.

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